bluuebunny/crossref_metadata_2025 huggingface dataset:
Difference between beta‐1‐selective and non‐selective beta‐blockade during continuous and intermittent exercise
Authors: Gullestad L. , Dolva L. Ø. , Søyland E. , Kjekshus J.
Published: April 2008

Summary. Limiting factors of maximal exercise performance are not clearly defined. In order to differentiate between various factors, maximal exercise was studied during continuous (n= 12) and intermittent (n= 9) exercise. The non‐selective beta‐blocker timolol (10 mg b.i.d. for 5 days) was compared double‐blind and placebo controlled with the beta‐1‐selective beta‐blocker metoprolol (100 mg b.i.d. for 5 days), with respect to effect on maximal exercise tolerance. Total cumulated work was comparable during continuous and intermittent exercise. Timolol and metoprolol reduced maximal exercise performance. No difference was observed between the two beta‐blockers during intermittent exercise. The non‐selective beta‐blocker caused a greater reduction in exercise performance (10·4%) than the beta‐1‐selective beta‐blocker (4·7%) (P<0·05) during continuous exercise. Maximal heart rate was higher with metoprolol than timolol during continuous exercise. The non‐selective beta‐blocker caused a slightly greater inhibition of lipolysis than the beta‐1 selective one. No significant differences in glucose concentrations were observed between the treatment regimens. Exercise caused a marked increase in serum potassium concentrations. Beta‐blockade caused further increase in potassium at any given workload. This study indicates that maximal working capacity is comparable during continuous and intermittent exercise. Beta‐1‐selective and non‐selective beta‐blockade reduce the maximal working capacity, non‐selective more than beta‐1‐selective. Substrate availability was not responsible for the beta‐blocker induced reduction of the working capacity. The rate of rise in serum potassium was significantly higher during beta‐blockade and may, therefore, be a limiting factor for the maximal working capacity.
Multiple breath nitrogen dead space
Authors: Arborelius M. , Rosberg H. E. , Wiberg R.
Published: April 2008

Summary. Ventilatory efficiency for eliminating CO2 is expressed by the physiological dead space, VDphys = (1‐PE CO2/Pa CO2) ×VT, where PE is the mixed exhaled and Pa the arterial CO2‐tension and VT the tidal volume. We used data from the multiple breath N2‐wash‐out with oxygen for calculating a functional dead space for nitrogen. VDFN2= (1 ‐FEN2/FEN2/FidN2) ×VT. FEN2 is the mixed exhaled N2‐fraction and FidN2 the calculated mean alveolar N2‐fraction during a wash‐out with the same number of breaths to reach 2% N2 in end tidal air, but having completely even distribution. FidN2 is shown to be 0·20±0·01 for wash‐outs using 20–150 breaths. The method was applied to wash‐outs from 21 healthy volunteers, 18 patients with chronic obstructive lung disease and two subjects with acute bronchospasm. VDF was well related to VD phys CO2 (r= 0·78) but higher than the latter. In subjects with lung disease VDF was inversely related to the degree of obstruction expressed by forced expiratory volume in one second per cent of vital capacity (r= 0·85). The subjects with bronchospasm had very high VD/VTMF, in relation to their FEV%. If airway dead space predicted from height and sex is subtracted from VDF, the resulting alveolar dead space will be a good expression for uneven gas distribution in the lungs. We also deduced a direct mathematical relation between lung clearance index and VD/VTF. The documented good reproducibility of LCI is thus also valid for VD/VTF, while the latter better expresses ventilatory efficiency.
Measurement of global and regional left ventricular performance with isotope technique in coronary heart disease
Authors: Boström P.‐Å. , Svensson M. , Lilja B.
Published: April 2008

Summary. In order to evaluate the left ventricular function in coronary artery disease, radionuclide measurements of global and regional ejection fraction (EF), regional wall motion and phase analyses of the left ventricular contraction were performed by equilibrium technique. One group of patients with angina pectoris and one group with myocardial infarction were compared with a control group. All the above‐mentioned parameters significantly separated the infarction group from the reference group both at rest and during work, while the group of patients with angina pectoris showed disturbances mainly during work, such as impaired ability to increase global and regional ejection fraction and regional wall motion.

Adding regional analysis and phase analysis to the global EF determination increases the possibility of studying the left ventricular function. However, this addition has a limited value in detecting impaired left ventricular function compared to the determination of just global EF in patients with angina pectoris and in patients with myocardial infarction.
Changes in atrial natriuretic factor during preload reduction with nitroglycerin in patients with congestive heart failure
Authors: Keller N. , Sykulski R. , Thamsborg G. , Storm T. , Larsen J.
Published: April 2008

Summary. Nine patients with congestive heart failure, New York Heart Association class II‐III, were evaluated with right heart catheterization. Plasma atrial natriuretic factor (ANF) was determined in blood samples from the pulmonary artery simultaneously with recordings of right atrial, pulmonary arterial, pulmonary capillary wedge and systemic arterial pressures and heart rate during preload reduction with 0·5 mg nitroglycerin sublingually. Basal plasma ANF levels were higher in patients with congestive heart failure compared to normal controls, and correlated to right atrial, pulmonary arterial, and pulmonary capillary wedge pressures. After nitroglycerin all patients had reductions in right atrial, pulmonary arterial, and pulmonary capillary wedge pressures and a simultaneous decrease in plasma ANF concentrations, reaching lowest values after 10 min. Central pressures and plasma ANF rose to baseline values within 30 min. After nitroglycerin plasma ANF concentrations correlated to pulmonary arterial and pulmonary capillary wedge pressures, while changes in plasma ANF correlated to changes in right atrial and pulmonary arterial pressures. These results provide further evidence that ANF is released by a pressure‐sensitive mechanism and demonstrates that ANF secretion in relation to central pressure variations is preserved in patients with congestive heart failure and that the response is rapid.
Kidney, lower limb and whole‐body uptake and release of catecholamines in alcoholic liver disease
Authors: Henriksen J. H. , Ring‐Larsen H. , Christensen N. J.
Published: April 2008

Regional (kidney, lower limb) and whole‐body kinetics of endogenous noradrenaline (NA) and tritium‐labelled L‐noradrenaline (3H‐NA) were determined in patients with alcoholic liver disease (one alcoholic hepatitis, 12 cirrhosis) and in control subjects (n= 6) in order to get information on the sympatho‐adrenal system in liver disease. Arterial NA was significantly elevated in ascitic patients (median 2·5 nmol/1, n = 9, P<0.05) as compared to non‐ascitic patients (1·6 nmol/1) and controls (1·7) nmol/l). NA spillover per unit NA inflow was increased in the kidney in patients with ascites (0·69 vs. 0·45 pmol/ming per pmol/min‐g in controls, P<0.005) but not in the lower limb (0·23 vs. 0·49 in controls, P<0·01). In patients with ascites the spillover rate of NA from the kidney into plasma (1·9 pmol/min·g) was significantly increased (P<0·02) compared to controls and non‐ascitic patients (1·2 and 1·0 pmol/min·g, respectively. Patients and control kidneys and limbs extracted almost the same fraction of 3H‐NA (0·34 vs. 0·32NS and 0·34 vs. 0·37 NS, respectively). Whole‐body clearance of 3H‐N A was not significantly different in cirrhotics and controls (median 0·89 vs. 0·91 1/min·m2), indicating that the raised NA in decompensated cirrhosis reflects enhanced sympatho‐adrenal activity rather than decreased metabolism of this amine. Our results do not point towards a uniform sympatho‐adrenal overactivity in decompensated cirrhosis, but rather indicate regional differences with different order of NA spillover. The renal sympathetic overactivity, as indicated by the increased renal NA overflow, is likely to be important to the decreased renal perfusion and increased saltwater retention characteristic of this clinical condition.
Myocardial turnover of plasma free fatty acids during angina pectoris induced by atrial pacing
Authors: Kaijser L. , Ericsson M. , Walldius G.
Published: April 2008

Myocardial extraction of free fatty acids (FFA), together with glucose, lactate, pyruvate, glycerol and oxygen was determined by simultaneous sampling of blood from an artery (a) and the coronary sinus (cs) at rest and during chest pains induced by atrial pacing in seven fasting male patients with ischaemic heart disease. Results were compared to those, at rest and during pacing at heart rate 140 beats min‐1in ten healthy men of similar age. A continuous i.v. infusion of14C oleate and3H palmitate enabled the calculation of simultaneous myocardial uptake and release of FFA. as well as of the fraction of extracted FFA which underwent direct oxidation. During chest pain lactate net extraction decreased to become, in some patients, negative. FFA extraction, as estimated from the fractional extraction of labelled fatty acid was likewise decreased, while the a‐cs O2difference was not significantly altered. The fractional oxidation of extracted FFA was increased, whereas the calculated fatty acid release from the heart was unaltered. The increase in fractional oxidation was quantitatively correlated with the decrease in lactate extraction suggesting that it was related to the degree or extent of ischaemia. It was also proportional to the decrease in FFA extraction. Thus, in patients with angina pectoris the ischaemic myocardium may be subjected to a limitation not only with regard to oxygen but also substrate flux into the myocardial cells.
The role of the endothelium in the control of venous tone: studies on isolated human veins
Authors: Thulesius O. , Ugaily‐Thulesius L. , Neglen P. , Shuhaiber H.
Published: April 2008

Summary. The role of the endothelium in the vasomotor control of veins was investigated in 14 isolated ring preparations of presumably normal saphenous veins obtained from vein grafts in connection with vascular surgery. The investigations were performed with the specimens mounted for recording isometric tension in organ baths. Paired rings were used, one normal and the other de‐endothelialized by gentle rubbing. The responses to noradrenaline (10‐8‐2 × 10‐5M), acetylcholine (10‐6M) and 120 mM KCI solution were tested.

After precontraction with 10‐7M noradrenaline, acetylcholine at 10‐6M did not induce cholinergic relaxation, but in the majority of experiments induced a further increase in tone. Maximal contraction with noradrenaline was significantly higher in normal compared to de‐endothelialized vessels. Therefore, endothelium‐derived relaxation as in arteries did not occur in human saphenous veins and the existence of an endothelial‐derived contracting factor in response to acetylcholine and noradrenaline is a possibility.
Determination of the oxygen cost of level walking
Authors: Linnarsson D. , Mattsson E. , Eklöf L. , Broman L. , Broman M. , Broström L. Å.
Published: April 2008

Summary. We have developed devices and methods for the determination of the oxygen cost of level walking. Oxygen uptake is determined with an argon dilution method. The validity of this technique is demonstrated. Walking speed is recorded and controlled by means of a speedometer cart. The reproducibility of a convenient, self‐selected walking speed and of a predetermined speed was studied. Coefficients of variation were below two per cent. Corresponding values of the oxygen cost of walking at a predetermined speed were three per cent or less up to an interval between tests of six months. We conclude that the proposed methods are suited for longitudinal studies of the oxygen cost of level walking, for example in patients with walking disorders.
Age‐dependency of left ventricular filling dynamics and relaxation as assessed by pulsed Doppler echocardiography
Authors: Myreng Y. , Nitter‐Hauge S.
Published: April 2008

Summary. Left ventricular diastolic function was assessed from transmitral flow velocity curves as measured by Doppler echocardiography in healthy individuals aged 21–69 years, each decade comprising 12 subjects. By ageing, progressive changes in the various filling parameters were observed. When comparing the youngest and oldest age groups, the ratio between peak velocities in early and late diastole decreased from 2.0±0.3 to 1.2±0.3 (P<0.001). The filling fraction of first third of diastole decreased from 54 ± 5% to 45 ± 4% (P<0.001). Isovolumic relaxation time increased from 61 ± 11 ms to 77 ± 12 ms (P<0.01). Correlation coefficients of velocity ratio, filling fraction and isovolumic relaxation time vs. age were r= ‐0.71 (P<0.001), r= ‐0.56 (P<0.001) and r= 0.44 (P<0.001), respectively. When isovolumic relaxation time and age were used together in multivariate regression analysis, only age was an independent predictor of velocity ratio and filling fraction. Stroke volume, peak velocity in left ventricular outflow tract, heart rate and systolic blood pressure were similar in all age groups. Thus, velocity ratio and filling fraction indicated a relative filling shift towards late diastole by ageing and were more sensitive than s̄ystolic parameters in reflecting age‐related changes in cardiac function. The changes could be explained neither by delayed relaxation nor by change in systolic parameters. When using Doppler echocardiography for evaluation of left ventricular filling, agematching of reference groups is necessary.
99Technetiumm DTPA does not break down during ultrasound nebulization
Authors: Groth S. , Funch‐Rosenberg H. , Mortensen J. , Rossing N.
Published: April 2008

Summary. For several years aerosolized 99Tcm‐DTPA has been used for studies of pulmonary permeability. Comparable results have been obtained regardless of the 99Tcm‐DTPA having been nebulized in an ultrasound nebulizer or a jet nebulizer. It was therefore surprising when in a recent study it was observed that more than 90% of a commercially available 99Tcm‐DTPA (Squibb) was dissociated into 99TcmO4‐ and DTPA during ultrasound nebulization. To verify this observation we performed chromatography of seven commercially available DTPA‐labelling kits (including that of Squibb). Four different test preparations of each of the kits were analysed: (1) stock solution of 99Tcm‐DTPA; (2) heated (80°C) 99Tcm‐DTPA; (3) 99Tcm‐DTPA nebulized by a DeVilbiss ultrasound nebulizer; (4) 99Tcm‐DTPA nebulized by a Varic ultrasound nebulizer. In no case were we able to demonstrate more than 1·0% reduced pertechnetate (99TcmO2) or more than 0·9% free 99TcmO4‐ after either heating or ultrasound nebulization. A maximum of 5·6%99TcmO2 could be demonstrated in the stock solution if chromatography was done immediately after the preparation, but only 15 min later no more than 0·9%99TcmO2 was present. We conclude that there is no essential chemical breakdown of 99Tcm‐DTPA during ultrasound nebulization. Caution should be taken not to use the 99Tcm‐DTPA until 15 min after its preparation.
Evaluation of intermittent drainage of the renal pelvis as seen in the isotope renogram
Authors: Granerus G. , Måre K. , Sohtell L.
Published: April 2008

Summary. Intermittent drainage (ID) of the renal pelvis is probably due to episodes of aperistalsis in the pelvo‐calyceal system. The incidence of ID in adult patients referred for renography for various nephro‐urological conditions was found to be 4·5%. Presence of ID was not related to sex or age but more common at a low urine flow. It was then usually bilateral and interpreted as a normal phenomenon. If the urine flow at the renographic examination exceeded 2 ml min‐1, ID was typically unilateral and there was often a history of obstructive uropathy and dilatation of the renal pelvis. However, there were no signs of obstruction or flank pains in connection with the recording of ID and follow‐up studies did not disclose any deterioration of renal function. It is concluded that ID seen at renography during diuresis should not be regarded as evidence of obstruction of pelvic outflow but merely as an indication of a dilated upper urinary tract.
Body composition measurement by dual photon absorptiometry: comparison with body density and total body potassium measurements
Authors: Hassager C. , Sørensen S. Sølvsten , Nielsen B. , Christiansen C.
Published: April 2008

Summary. Body composition was measured in 29 healthy adults (12 men and 17 women) by three different methods: Dual photon (153Gd) absorptiometry (DPA), body density measurements (BD) and measurements of total body potassium (TBK).

Correlation and regression analysis with the body fat percentage (Fat%) measured by the three different methods gave r values between 0·83 and 0·90 and SEEs between 4·0 and 6·0 (Fat%). We conclude that DPA provides a new method of measuring body composition with precision and accuracy errors in the same range as the more established methods.
Plasma concentrations of adrenaline, noradrenaline and dopamine during forearm dynamic exercise
Authors: Hartling O. J. , Kelbæk H. , Gjørup T. , Nielsen M. Damkjær , Trap‐Jensen J.
Published: April 2008

Summary. In six healthy volunteers plasma concentrations of adrenaline, noradrenaline and dopamine were measured at rest and during dynamic forearm exercise at submaximal and maximal intensities. Arterial and venous concentrations of adrenaline and noradrenaline increased with forearm exercise at all workloads. Dopamine concentrations did not change. The increases in adrenaline and noradrenaline were almost linearly related to the increase in heart rate with no levelling off at maximal exercise intensities. It is concluded that dynamic exercise with the forearm muscle group causes a small but significant activation of the sympatho‐adrenal system as reflected by increases in plasma concentrations of adrenaline and noradrenaline.
Measurement of carboxyhaemoglobin by spectrophotometry and gas chromatography
Authors: Johansson M. B. , Wollmer P.
Published: April 2008

Summary. The purpose of this study was to evaluate state‐of‐the‐art spectrophotometry for measurement of carboxyhaemoglobin (COHb). We measured the fractional concentration of COHb in 109 blood samples from patients under investigation of anaemia or with exposure to carbon monoxide (smokers) with the OSM3 Hemoximeter and by gas chromatography. Duplicate measurements were made with both methods in 42 samples.

We found only a trivial systematic difference between the two methods. There was, however, a considerable scatter of the measurements, the limits of agreement (95% confidence limits for the difference between the two methods) being —0.98 and 0.86% COHb. The poor agreement between the methods was largely explained by a large random scatter in duplicate spectrophotometric measurements, whereas the method based on gas chromatography was highly reproducible.

We conclude that the low accuracy of spectrophotometric measurements of COHb precludes its use for assessment of the endogenous production of CO, but that it may be useful for assessment of exposure to exogenous CO.
Meal‐induced thermogenesis in previously obese patients
Authors: Thörne A. , Näslund I. , Wahren J.
Published: April 2008

Summary. Meal‐induced thermogenesis is reported to be reduced in obese patients and the purpose of this study was to find out whether thermogenesis after a mixed meal differs between previously obese(post‐obese) subjects and non‐obese controls. Nine post‐obese patients (body mass index 27 ±1) and nine age‐ and sex‐matched non‐obese volunteers (body mass index 22 ±1) were studied with continuous indirect calorimetry in the basal state and after the ingestion of a standardized test meal. Following treatment with vertical banded gastroplasty for the obesity, the weight of the patients had decreased by an average of 44 ± 5 kg.

Basal oxygen uptake and energy expenditure did not differ between the post‐obese and the controls. After the meal, energy expenditure increased rapidly, becoming relatively constant after 60 min; the average increase above basal was in the post‐obese 30·5 ± 1·8% and in the non‐obese controls 29·5 ±2·3% (NS). In absolute terms, the increments above basal were also similar in the two groups. The heart rate was higher in the post‐obese group throughout the study period.

It is concluded that the thermogenic response to a mixed meal is much the same in post‐obese subjects and in non‐obese controls. These findings support the notion that a decreased meal‐induced thermogenesis is a secondary phenomenon rather than a primary pathogenic factor in human obesity.
Lung function in patients with prior poliomyelitis
Authors: Borg K. , Kaijser L.
Published: April 2008

Summary. Lung volumes and spirometric flows, maximal respiratory pressures, lung diffusion capacity and blood gases were evaluated in 20 patients with prior poliomyelitis and compared with data from an age‐ and sex‐matched control group. In the polio patients, static lung volumes and pulmonary flow capacity were significantly reduced to approximately 65% of the values of the control group. However, expiratory and inspiratory flows were normal in relation to lung volumes, while maximal respiratory pressures were significantly reduced in the polio patients. Static lung volumes and forced flows were correlated with the maximal respiratory pressures both in the polio patients and in the controls. However, when the muscle force in the polio patients decreased below a certain level, it became more important as a determinant of lung‐flow capacity. The polio patients had a significantly increased Pco2 but a normal oxygen saturation and Pco2 was inversely correlated with the maximal respiratory pressures in the patients but not in the controls. The lung diffusion capacity was reduced in the polio patients compared to the controls, but less markedly than vital and total lung capacity.

The findings indicate a restrictive respiratory dysfunction and alveolar hypoventilation most probably due to weakness of the respiratory muscles.
Is central chemoreceptor sensitive to intracellular rather than extracellular pH?
Authors: Lassen N. A.
Published: April 2008

Summary. The chemosensitive area on the ventral surface of the brain stem responds to local acidosis by eliciting hyperventilation and to local alkalosis by hypoventilation. The stimulus is conventionally thought to be the hydrogen ion concentration in the area's extracellular fluid. It is pointed out, however, that the elegant studies by Loeschcke & Ahmad have demonstrated that [pH]c and [pH]i are normally tightly and rapidly coupled (Loeschcke & Ahmad, 1980). For this reason, the stimulus might just as well be the intracellular hydrogen ion concentration in the chemoreceptor area.

The administration of acetazolamide allows the dissociation of [pH]c from [pH]i. With acetazolamide a sharp acid shift of CSF pH ([pH]c) is measured and in consonance with this shift a marked increase in CBF is seen. Comparing these two reactions to that obtained with CO2 breathing, it is apparent that 7% CO2 causes about the same decrease in [pH]c and the same increase in CBF. In other words CBF acidosis can quantitatively account for the CBF increase induced by acetazolamide. But CO2 and acetazolamide influence [pH]i quite differently, as CO2 drops [pH], to almost the same extent as [pH]i, while two recent studies by MR spectroscopy have shown that acetazolamide does not drop [pH]i measurably, if tissue hypercapnia is prevented in artificially ventilated rabbits or by the mild spontaneous hyperventilation caused by acetazolamide in normal man.

The lack of measurable intracellular acidosis with acetazolamide accords with the very mild hyperventilation seen in man: the very high gain of the chemoreceptor response means namely that the approximate 10% drop in end‐expiratory Pco2 seen in man should result from a local acid shift of only 0·002 pH units, a shift much too small to be measurable by the technique used. If, on the other hand, [pH]c were the chemoreceptor stimulus, then it is surprising that 2 g of acetazolamide did not cause the same many‐fold increase in alveolar ventilation as 7% CO2, as the [pH]c acid shift is practically the same for the two stimuli.

The [pH]c and [pH]i values referred to stem from global measurements. But the data regarding blood flow and Pco2 of the chemoreceptor area combined with histological evidence suggest that the acid‐base balance extra‐ and intracellularly of the area is just as for the brain as a whole. Therefore, the simplest hypothesis explaining the dissociation of the responses to CO2 and acetazolamide with respect to ventilation and to [pH]i is to assume that it is [pH]i and not [pH]c that is the chemoreceptor stimulus.
The effect of calcitonin gene‐related peptide (CGRP) on human forearm blood flow
Authors: Jernbeck J. , Edner M. , Dalsgaard C. ‐J. , Pernow B.
Published: April 2008

Summary. The effect of intravenous and intra‐arterially administered calcitonin generelated peptide (CGRP) on the human forearm blood flow and cutaneous blood flow were investigated by means of venous occlusion plethysmography and laser‐Doppler flowmetry, respectively. Infusion of CGRP (11–216 pmol min‐1) into the brachial artery resulted in a dose‐dependent increase in forearm blood flow and cutaneous blood flow which persisted for up to 90 min after the infusion was stopped. Repeated infusions resulted in an identical response. Systemic intravenous infusion of CGRP (104–520 pmol min‐1) resulted in a dose‐dependent flush in the face, neck, upper trunck and upper arms, and an increase in the forearm blood flow. The cutaneous blood flow was dramatically increased on the forehead, whereas on the hand only a slight increase was noted. By intravenous infusions a significant drop in blood pressure and increase in heart rate were seen at 520 pmol min‐1. Thus, it is possible to give CGRP in doses that increase the blood flow in muscle and skin without resulting in a fall in systemic arterial blood pressure and tachycardia, suggesting that CGRP may be used as a tool for the treatment of various conditions in man with compromised blood flow.
Respiratory variability and associated cardiovascular changes in adults at rest
Authors: van den Aardweg J. G. , Karemaker J. M.
Published: April 2008

Summary. Breathing patterns and associated circulatory fluctuations may reflect the action of various regulatory mechanisms as well as mechanical influences of breathing on the circulation. Thus, the study of such patterns can enhance our knowledge of these mechanisms, both in normal and pathological conditions. In this review, literature is evaluated that provides insight into the breath‐to‐breath variation of respiration in quietly breathing adults. Also when respiration is seemingly random, deterministic patterns in the respiratory variability can often be discerned. The various methods used in the recognition of such patterns and their possible interpretation are discussed.

Furthermore, the question is addressed how respiratory variability can affect the circulation and how this can be studied by analysing the time relationships of respiratory and circulatory parameters. This may add to both the understanding of normal cardiovascular regulation and to insight into cardiovascular disturbances under unstable respiratory conditions. As examples of such circumstances, some common conditions are discussed that are often, though not always, associated with pathology, viz. Cheyne‐Stokes respiration, snoring and the sleep apnoea syndrome.
Atrial natriuretic peptide concentrations in umbilical cord plasma from pre‐eclamptic women
Authors: Matzen S. , Nielsen J. , Christensen J. , Schütten H. J. , Knigge U. , Warberg J.
Published: April 2008

Summary. Atrial natriuretic peptide (ANP) was measured in arterial and venous umbilical cord plasma at the time of delivery by cesarean section in pre‐eclamptic (n= 7) and normal women (n= 6). In addition venous samples were obtained from pre‐eclamptic (n= 7) and normal pregnant women (n= 7) near term. ANP plasma levels were higher in pregnant women with pre‐eclampsia than in normal pregnant women (27·9±4·4 [mean±SEM] and 14·1 ±2·5 pmol 1‐1, respectively, P<0·05). Immediately after delivery plasma ANP in pre‐eclamptic mothers was 66·7 ± 12·8 pmol 1‐1 compared to 13·9 ±2·2 pmol 1‐1 in normal mothers (P<0·01). However, in the pre‐eclamptic group the levels of ANP in arterial and venous umbilical cord plasma (19·5 ±4·2 and 16·7±4·3 pmol 1‐1 respectively) were significantly (P<0·01) lower than ANP levels in arterial and venous cord plasma (39·6 ± 1·0 and 31·1±4·2 pmol 1‐1, respectively) from normal mothers. It is concluded that the increased ANP plasma level in pre‐eclamptic women originates from a maternal source. In addition, since the ANP level is lower in cord plasma than in maternal plasma in pre‐eclampsia, fetoplacental volume homeostasis may also be changed in pre‐eclampsia.
Low‐frequency transcutaneous nerve stimulation in mild/moderate hypertension
Authors: Kaada B. , Flatheim E. , Woie L.
Published: April 2008

Summary. Low‐frequency peripheral nerve stimulation may induce widespread cutaneous and muscular vasodilatation in animals and humans due to sympatho‐inhibition. This response has in humans been shown to be associated with a lowering of the systemic vascular resistance and arterial pressure.

In the present study the effectiveness of low‐frequency (2 Hz) transcutaneous electrical nerve stimulation (TNS) has been examined in 46 patients, all 41–43 years of age, with a primary diagnosis of uncomplicated mild/moderate hypertension (90–115 mmHg diastolic pressure). The study was designed blind with matched controls in a TNS group and a placebo group. The blood pressure was measured objectively with an automatic monitor. In a short‐term experiment TNS produced a significant lowering of systolic, mean arterial, and diastolic pressures amounting to 8 mmHg (P<0·01), 6 mmHg (P<0·01), and 4 mmHg (P<0·02), respectively. In a long‐term study, after 2 weeks of daily stimulation, a similar depression was recorded with no stimulation on the day of examination. An eventual clinical use of the depressor effect of TNS demands further clinical research.
Evaluation of the dynamic cutaneous post‐ischaemic hyperaemia and thermal response in elderly subjects and in an area at risk for pressure sores
Authors: Schubert V. , Fagrell B.
Published: April 2008

Summary. The response of skin blood cell flux (SBF) to locally applied pressure was evaluated with the laser‐Doppler technique in the areas of the sacrum and the gluteus maximus muscle of geriatric patients and healthy young and elderly subjects.

The SBF over the sacrum stopped at a lower external skin pressure than over the gluteus muscle in all groups studied (P<0·05·0·001). The SBF at rest was lower among geriatric patients and over the sacrum, with men showing the lowest value (P<0·001). The initial slope of the SBF curve and the peak SBF during the post‐occlusive reactive hyperaemia (PRH) were lower among geriatric patients compared to younger healthy subjects (P<0·05·0·01) over both areas studied. During the last part of the PRH response rhythmic oscillations started, known as vasomotion.

The mean skin temperature at rest was higher over the sacrum (P<0·001) than over the gluteus area, but no difference was found between the groups. The temperature increase during the PRH was larger over the gluteus muscle (P<0·01) than over the sacrum area in the healthy subjects. Among the patients the temperature increase was larger over the gluteus only during the first half of the PRH, after which the temperature increased most over the sacrum.

It is concluded that SBF and skin temperature show different responses in microvascular reactivity to external pressure in elderly vs. younger subjects and also between sexes. The described technique may be useful in clinical practice for predicting the risk of pressure sores in different areas and subjects.
Transcutaneous oxygen tension measurements in the assessment of limb ischaemia
Authors: Quigley F. G. , Faris I. B.
Published: April 2008

Summary. The measurement of transcutaneous oxygen tension (TcPo2) has been adapted for the assessment of the blood supply of the lower limb. This study was undertaken to determine the most useful means of expressing TcPo2 measurements. We studied 176 patients with peripheral vascular disease and/or diabetes and 34 normal volunteers. Approxiately half of the patients studied had ulceration or gangrene of the foot. A comparison of three methods of expressing TcPo, measurement for predicting presence of ulceration was made using ROC A analysis. The absolute value of TcPo, on the dorsum of the foot was the best predictor of the presence of ulceration or gangrene. An absolute value of TcPo, of 30 mmHg on the dorsum of the foot had a sensitivity of 42% and specificity of 91%. The sensitivity of the test was as good in diabetic patients as in non‐diabetic patients.
Recoveries of phosphatidylcholine and alveolar macrophages in lung lavage from healthy light smokers
Authors: Schmekel B. , Khan A. R. , Linden M. , Wollmer P.
Published: April 2008

Summary. Twenty‐one healthy volunteers, 11 light smokers and 10 non‐smokers, were studied by broncho‐alveolar lavage. The levels of the phosphatidylcholine (PC) in broncho‐alveolar lavage were measured and used as an index of surfactant. The PC levels in broncho‐alveolar lavage obtained from the smokers were significantly lower than in lavage fluid from the non‐smokers. There was an inverse correlation between PC levels and cumulated tobacco smoke exposure, as estimated by the number of pack‐years, and to current smoking habits as estimated by the number of cigarettes smoked per day. The number of alveolar macrophages was significantly higher in broncho‐alveolar lavage obtained from smokers, and there was a significant inverse correlation between PC levels and numbers of alveolar macrophages in the lavage fluids. The potential role of alveolar macrophages in the elimination of surfactant lipids is discussed.
The effect of forced expirations on mucociliary clearance in patients with chronic bronchitis and in healthy subjects
Authors: Mortensen J. , Jensen C. , Groth S. , Lange P.
Published: April 2008

Summary. Animal studies have shown that frequent coughing may damage the mucociliary apparatus in flow‐limiting segments of the central airways. To determine whether mucociliary clearance in humans is affected by repeated dynamic compression associated with forced expirations, we measured pulmonary deposition and mucociliary clearance for 2 h of inhaled [99Tcm]albumin. The subjects inhaled [99Tcm]albumin on 2 study days (randomized) using (A) slow inspirations and forced expirations, while inhalation using (B) forced inspirations and slow expirations served as control. The study was conducted using 10 patients with chronic hypersecretory/obstructive bronchitis and six normal subjects. We found that inhalation of [99Tcm]albumin by the two manoeuvres (A and B) resulted in similar patterns of aerosol deposition. There was no significant difference in retention of radioactivity in the central lung region at 1 h in the patients with chronic bronchitis after inhalation with manoeuvre A (102%) and with manoeuvre B (91.5%), or in the healthy subjects after manoeuvre A (74%) and manoeuvre B (77%). There was also no difference in the retention at 2 h or in overall mucociliary clearance in any of the groups.

We conclude that dynamic compression in the central airways associated with forced expiration does not affect bronchial clearance in the airways of healthy subjects or in patients with chronic bronchitis.
Arterial and venous measurement in resting forearm of metabolic indicators during rest and leg exercise
Authors: Nordrehaug J. E. , Bjørkhaug A. , Danielsen R. , Vik‐Mo H.
Published: April 2008

Summary. We compared the levels of various metabolic indicators in arterial and venous forearm blood during maximal treadmill leg exercise, and the subsequent 9 min in nine volunteers aged 31–56 years. At maximal exercise plasma lactate was 13·2 ± 3·1 mmol 1‐1 arterially, while venous was 41% lower, but increased more than arterial after exercise. There was a linear relationship between arterial and venous samples during and after exercise, but not at baseline. Plasma pyruvate increased on the arterial side from 49 ± 8 to 172 ± 30 μmol 1‐1 at maximal exercise, maximal venous was 21% lower. Free fatty acids were not different at rest, but decreased during exercise by 52 and 38% on the arterial and venous side. There was no relationship between arterial and venous levels. Changes in these three variables occurred significantly earlier on the arterial side. Arterial cyclic AMP rose from 97·3 ± 28·4 to 262·7 ± 67·5 nmol 1‐1 from rest to exercise, and was linearly inversely related to the decrease in free fatty acids. The mean venous pH was lower than arterial at rest, but was the same as arterial at maximal exercise and after. Thus, venous plasma lactate and pyruvate, but not free fatty acids, are linearly related to arterial measurements during maximal exercise, while pH is identical. Non‐working muscle modifies exercise‐induced changes, and therefore venous and arterial forearm blood sampling give more information than either alone.
Splanchnic and renal vasoconstriction during neuropeptide Y infusion in healthy humans
Authors: Ahlborg G. , Weitzberg E. , Lundberg J. M.
Published: April 2008

Summary. To assess whether neuropeptide Y (NPY) causes vasoconstriction in human splanchnic and renal tissues, six healthy subjects were given NPY intravenously in the basal resting state for 15 min. The NPY dose of 10, 25, and 50 pmol kg‐1 min‐1 was increased every 5 min. The infusion was accompanied by elevated arterial plasma levels of NPY‐like immunoreactivity (Li) which were 15, 40, and 85 times higher than the basal value. After the infusion plasma NPY‐Li fell with two half‐lives of 5 ±0.4 and 29± 1.7 min but was still 4 times the basal values 60 min after the infusion (P<0.01). A vasoconstrictor effect was seen at about 500 pM plasma NPY‐Li. During the NPY infusion splanchnic and renal blood flows decreased by 26% and 29% respectively. The blood flows in these regions were still below the basal value 40 to 60 min after the NPY infusion. Plasma noradrenaline fell by 20% (P<0.02) and arterial glucose by 3% (P<0–005) during the NPY infusion. It is concluded that NPY causes a dose‐dependent long‐lasting vasoconstriction in human renal and splanchnic tissues. The results also suggest that elevated plasma NPY‐levels may be associated with changes in the turnover of noradrenaline and glucose.
Effects of sulphur hexafluoride on psychomotor performance
Authors: Östlund A. , Sporrong A. , Linnarsson D. , Lind F.
Published: April 2008

Summary The narcotic influence of sulphur hexafluoride on mental and psychomotor performance has been studied in 9 subjects at normal atmospheric pressure. Control experiments were performed with air and with nitrous oxide. Psychomotor, perceptual and cognitive abilities were assessed using a computerized test battery. Subjects were exposed to air and six different normoxic gas mixtures: 13, 26, and 39% N2O, and 39, 59, and 79% SF6. Significant performance impairments were found with 13% N2O and gradual further impairment with 26, and 39% N2O. During exposure to 39, 59, and 79% SF6 over‐all performance was impaired by 5, 10, and 18%, respectively. Impairment was significant with 59 and 79% SF6. The results indicate that the relative narcotic potency of SF6: N2O is about 1:4 in humans. It is concluded that a normoxic SF6‐O2 mixture can be inhaled for lung function studies without any harmful effects and that the short‐lasting narcotic effect, although detectable with a test battery, would not impair the ability of the subject to perform simple breathing procedures.
The creatine kinase system in the serum of runners following a doubling of training mileage
Authors: Apple F. S.
Published: April 2008

Summary This study examined the response of the serum creatine kinase (CK) isoenzyme/isoform system following the stress of successive weeks of increased training. Four highly‐trained male long‐distance runners doubled their training mileage [45.0 (SD 3.5) to 81.2 (4.7) miles] for 3 weeks. Venous blood samples were obtained prior to the start of the increased training period and at the end of each week, days 7, 14, and 21, 12 h after a training run. All runners experienced a significant increase in training perception difficulty, which correlated with the significant increase in training mileage. While total CK activities did not become significantly elevated until day 14, the tissue isoform CK‐MM3, as well as the ratio of CK‐MM3 to MM1 (final CK‐MM degradation isoform) became significantly elevated at day 7 and remained elevated throughout day 21. These findings demonstrate that an increase in training mileage caused a significant and continuous release of tissue CK activity from skeletal muscle into the circulation.
Redistribution of skin blood flow during leg dependency in peripheral arterial occlusive disease
Authors: Scheffler A. , Jendryssek J. , Rieger H.
Published: April 2008

Summary A disturbed autoregulation of cutaneous blood flow in legs with peripheral arterial occlusive disease (PAOD) has previously been demonstrated for circumscribed skin areas. In the present study, posturally‐induced changes of skin perfusion distribution along ischaemic limbs were investigated topographically in 35 PAOD patients by means of fluorescein perfusography. Among the 68 legs studied, 7 had patent arteries and 61 could be assigned to FONTAINE stages I to IV. Limbs with peripheral skin lesions (stage IV) were further differentiated according to either healing (stage IV+) or non‐healing (stage IV‐) on conservative treatment. Sitting‐up always led to prolonged calf as well as foot fluorescein appearance times (AT) except for legs in stage III or IV‐ disease. In the latter two groups, decreased sitting as compared to supine AT foot‐to‐calf ratios indicated a relative shift of dye delivery from proximal towards distal skin regions during posture. In contrast, this measure of blood flow redistribution did not change in the other groups. The redirection of fluorescein influx was significantly correlated with the systolic arterial pressure ankle‐to‐arm ratios. In conclusion, besides small perfusion pressure increases or passive microvessel distension, a shift of the peripheral resistance ratios may contribute to the improved blood supply of ischaemic skin regions during leg dependency. An arteriolar vasoparalysis does not regularly exist in limbs with skin lesions not primarily originating from ischaemia (stage IV+).
Sham‐feeding decreases cardiac output in normal subjects
Authors: Andersen H. Bryde , Jensen E. Winther , Madsbad S. , Nielsen S. L. , Burcharth F. , Christensen N. J.
Published: April 2008

Summary The cardiovascular effect of sham‐feeding was measured in seven healthy non‐obese human subjects by the Fick principle using the carbon dioxide rebreathing method. The subjects were resting in the sitting position and were exposed to the sight and smell but not the taste of a breakfast meal. Cardiac output decreased significantly from a mean value of 40.1 min‐1 to 3.5 1 min‐1 during sham‐feeding (Friedman, P= 0.004). The cardiac output returned to basal values in all seven subjects when the sensory stimulus was removed. The decrease in cardiac output was due to a decreased stroke volume, whereas heart rate and blood pressure did not change. The mechanism of the decrease in cardiac output during sham‐feeding remains to be established.
Gravitational stress and volume regulation
Authors: Norsk P.
Published: April 2008

Summary. During the past 3 decades, groundbased experiments have been performed in order to investigate the effects of increased and decreased gravitational stress, respectively, on the renal response in humans. Experiments that simulate an increase in gravitational load (+GZ) to the subjects (centrifugation, passive head‐up titlt [HUT] or lower body negative pressure [LBNP] have clearly demonstrated a decrease in renal sodium and water excretion. Simultaneously, increases in plasma levels of arginine vasopressin (AVP), renin activity (PRA), aldosterone (PA), norepinephrine (NE) and decreases in ANP have been observed. Additionally, experiments that have utilized immersion of seated subjects to simulate a decreased gravitational stress (˜0 Gz) have demonstrated that renal water and sodium excretion increases by 100–400% and that plasma AVP, PRA, PA, and NE concentrations are reduced and ANP levels increased. Alternative experimental models conducted to simulate the effects of weightlessness in humans such as head‐down tilt (HDT) and lower body positive pressure (LBPP) have yielded less consistent results than those of water immersion (WI) with respect to renal function. However, compared to a seated control HDT clearly induces an increased rate of renal fluid and sodium excretion. The demonstration that central volume expansion during WI is accompanied by an increase in renal fluid and electrolyte excretion and that central hypovolemia during centrifugation, HUT, and LBNP is accompanied by the opposite effects indicate that changes in central blood volume is an important determinant of the renal functional changes. Results of experiments in humans during weightlessness in space are inconsistent and difficult to interpret. However, they have indicated that a cephalad redistribution of blood and fluid occurs and that this is accompanied by a decrease in total body fluid. Experimental models that, respectively, increase and decrease the gravitational stress in humans constitute promising tools in the investigation of the physiology and pathophysiology of volume regulation.
Distribution of radioactive aerosol in the airways of children and adolescents with bronchial hyper‐responsiveness
Authors: Backer V. , Mortensen J.
Published: April 2008

Summary. The purpose of this study was to examine the relationship between the pulmonary distribution of inhaled radioaerosol, bronchial responsiveness, and lung function in children and adolescents. The participating subjects (n= 39) were divided into three groups: (1) 14 asthmatics with bronchial hyper‐responsiveness (BHR), (2) five non‐asthmatic subjects with BHR, and (3) 20 controls without BHR. Pulmonary distribution of [99Tcm) albumin radioaerosol, maximal expiratory flow when 25% of forced vital capacity remain to be exhaled (MEF25), and bronchial responsiveness to inhaled histamine were measured. Twenty subjects (52%) had irregular central distribution and 19 subjects (48%) had regular distribution of radioaerosol in their lungs. No difference in distribution of radioaerosol was found between the three groups of children. The median MEF25 among non‐asthmatic subjects (80% predicted) was lower than that found in controls (92% predicted) but higher than that found in asthmatic subjects (55% predicted). A relationship was found between reduced flow at the peripheral airways, as indicated by MEF25 and the degree of central distribution of radioaerosol. Furthermore, subjects with irregular central distribution of radioaerosol had an increased degree of bronchial responsiveness. In conclusion, children and adolescents who have flow rates in the peripheral airways or increased degree of bronchial responsiveness tend to have abnormal distribution of radioaerosols.