bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of immobilization of short duration on the muscle fibre size
Authors: Lindboe Christian Fredrik , Platou Christian Stoud 
Published: April 2008

Summary. In 10 patients with unilateral knee joint lesions, the injured leg was immobilized for 72 h by a plaster cast reaching from the hip to the ankle. At removal of the casts, open muscle biopsies were taken from the vastus medialis muscle on both sides. The muscle specimens were stained for myofibrillar ATPase activity and muscle fibre areas were measured on transverse sections. The differences in fibre size between the two sides were registered and statistically evaluated.The reduction in fibre size on the immobilized side was 14.4% for the type 1 fibres and 17.3% for the type 2 fibres, respectively. However, these differences were not significant because of considerable variations from case to case, with an increase in fibre size on the immobilized side in three cases.It is concluded that short time post‐traumatic immobilization may have variable effects on the muscle fibre size and that one single biopsy might be insufficient to disclose early disuse atrophy whereas the method may be useful in cases of longer duration.
Long‐term monitoring of arterial pO2 in burned patients
Authors: Nilsson Erling , Arnandery Claes 
Published: April 2008

Summary. Five patients, who were treated in a special ward for bums were followed by continuous intra‐arterial pO2 monitoring for a total of 1612 h (range 13–604 h). The pao2 catheter electrodes used were surface‐heparinized, and inserted either in the radial or the femoral artery. Some electrodes were accidentally withdrawn. Recalibration was performed for two of the 10 electrodes used. These electrodes presented a changed sensitivity after heavy stretching of the sensor during the nursing. The sensitivity of one of these electrodes was altered downwards and the other one upwards. After recalibration the pao2 electrodes presented accurate values for the rest of the monitoring period. Without compensation for drift, the pao2 electrode readout was compared to the results of traditional blood‐gas analysis, which served as a reference. The regression function found was y = ‐0·62+ 1·04x (r=0·93, SD=1·40, n=60).The blood flow velocity around some of the pao2 electrodes was studied by the pulsed Doppler technique. There was no influence of the surface‐heparinked pao2 electrode on the femoral artery blood flow velocity as compared to the contralateral, non‐catheterized femoral artery. The blood flow velocity proximal to a traditional radial artery catheter was compared to the flow velocity in the contralateral radial artery containing a surface‐heparinized pao2 electrode. The surface‐heparinked electrode did not decrease the mean flow velocity in contrast with the traditional radial artery catheter, which had to be withdrawn after 8 days because of clotting. The surface‐heparinized catheter electrode was still monitoring pao2 accurately after 25 days in the artery, which was the longest period studied for a particular sensor.
NONINVASIVE PULMONARY BLOOD FLOW FOR OPTIMAL PEEP
Authors: Gedeon A. 
Published: April 2008

SUMMARYRecent data in the literature suggest that effective pulmonary blood flow (Q) measured invasively as cardiac output minus shunt flow, assumes its largest value at a PEEP level that is optimal in the sense that it also provides close to maximal oxygen delivery. Qp obtained noninvasively from simultaneous measurements of mixed expired and end‐tidal CO2‐concentrations is therefore proposed as a simple clinical indicator of the effects of PEEP on the cardio‐pulmonary system. It is shown that modern respiratory equipment can be easily adapted to implement such a noninvasive evaluation of PEEP therapy. If the method is proven useful an automatic search for optimal PEEP becomes a future possibility.
Autonomic cardiovascular responses in old age
Authors: Kaijser Lennart , Sachs Charlotte 
Published: April 2008

Summary. The effect of age on autonomically mediated cardiovascular responses to certain manoeuvres was studied in 15, healthy, old men and women (60–80 years). The results were compared with groups of healthy young (about 25 years) and middle‐aged (about 45 years) subjects. There was no significant reduction in cardiovascular responses between the young and middle‐aged groups. Respiratory sinus arrhythmia, and heart rate, blood‐pressure and contralateral forearm blood flow increases to isometric hand grip, as well as the heart rate decrease during a dive reflex test, were significantly attenuated in the old age group. The Valsalva ratio, and the heart rate and blood‐pressure changes during an 8 min orthostatic test did not differ between the old and the two younger age groups.There seems to be only a moderate attenuation of autonomic cardiovascular responses to about 60 years, after which there is a more rapid decline. The difference in reduction between different responses, even those mediated by the same type of autonomic nerve, suggests that the decreased responses are not due to an isolated impaired function of the peripheral autonomic nerve. The impairment may be due to the receptor organ or a combination of defects in function of several parts of the autonomic nervous system in old age.
Cardiovascular responses and plasma catecholamines in old age
Authors: Sachs Charlotte , Hamberger Bertil , Kaijser Lennart 
Published: April 2008

Summary. Plasma catecholamines and haemodynamic responses to isometric handgrip, orthostatic body position and dynamic cycle exercise were studied in 10 healthy old men (mean age 71 years) and 10 healthy young men (mean age 26 years). At rest, plasma noradrenaline (NA) was significantly higher in the old age group. During handgrip there were greater increases in heart rate and blood‐pressure in the young rather than in the old men, while forearm blood‐flow increase was similar in the two age groups, and there was no increase in NA in either groups. In the orthostatic position heart rate increased in the young men only, and forearm blood‐flow decreased more in the young than in the old men. NA concentration increased similarly in both age groups. During dynamic exercise the increases in both the heart rate and the blood‐pressure, at similar relative submaximal as well as maximal loads, were smaller in the old men. At maximal work NA and adrenaline (A) concentrations were higher in the young men, while at the lowest load, NA concentration was higher in the old men. Similar increases in exercise heart rate, blood‐pressure or rate of perceived exertion corresponded to lower increases in NA in the old men.It can be concluded that old men, compared with young men, have a reduced maximal capacity to release NA and A upon provocation. In addition, the sensitivity for catecholamines in the target organ is reduced with age, as suggested by the smaller increases in heart rate and blood‐pressure for a given increase in NA during exercise. The higher basal NA level and the higher NA level, during moderate provocation, may suggest a compensatory increase in activity.
Pulmonary clearance of inhaled 99mTc‐DTPA: effect of surfactant depletion in rabbits
Authors: Wollmer P. , Evander E. , Jonson B. , Lachmann B. 
Published: April 2008

Summary. We examined the effect of surfactant depletion on the rate of pulmonary clearance of inhaled 99mTc‐diethyl‐triamino‐penta‐acetate (DTPA). 99mTc‐DTPA was administered as a fine aerosol to four control animals and to four animals after wash‐out of pulmonary surfactant. Care was taken to minimize structural damage to the lavaged lungs. Clearance of 99mTc‐DTPA was measured over the right lung by external counting. The clearance rate was substantially increased in the lavaged animals compared to the control animals.We conclude that the pulmonary surfactant system is a rate‐limiting factor for the absorption of inhaled 99mTc‐DTPA. Measurement of the pulmonary clearance of 99mTc‐DTPA may provide a new means for studying the pathogenetic role of the surfactant system in a variety of lung diseases.
Repeatability of the single‐breath method for estimation of pulmonary blood‐flow: comparison among four data‐reduction procedures
Authors: Christensen P. , Grønlund J. 
Published: April 2008

Summary. The single‐breath method of Kim, Rahn and Farhi (1966) enables the estimation of the pulmonary blood‐flow from the Pco2 vs. Pco2 curve recorded during a prolonged expiration. Studies on the repeatability of the method have given very different results. At one extreme the estimated pulmonary blood flows ranged from —47 to 173 litre/min and at the other extreme the repeatability was found to be better than that usually reported for invasive methods. A possible explanation for these important differences is the use of different data‐reduction procedures to calculate the pulmonary blood‐flow from the measured Pco2 and Po2 values.In the present study we have investigated the repeatability of the single‐breath method in 20 test subjects using four previously published data‐reduction procedures. Furthermore, we have studied the sensitivity of the estimated pulmonary blood‐flow to measurement noise for each of the four data‐reduction procedures, by using a previously described technique based on computer simulations. Three of the data‐reduction procedures gave standard deviations on repeated single determinations of the pulmonary blood‐flow of about 1 litre/min whereas the last method gave results which fluctuated wildly from one determination to the next. The simulation showed that about 1/3 of the random variations can be ascribed to the measurement noise in Pco2 and Po2.
Transthoracic electrical impedance at 1 and 100 kHz ‐ a means for separating thoracic fluid compartments?
Authors: Larsen F. F. , Mogensen L. , Tedner B. 
Published: April 2008

Summary. The electrical impedance of biological tissues varies with their water and electrolyte contents. Alternating current above 5–10 kHz passes both intra‐ and extracellular fluid, and lower frequency current preferentially extracellular fluid. In an attempt to evaluate thoracic fluid in different compartments, transthoracic electrical impedance (TEI) was measured at 1 and 100 kHz in 15 consecutive patients, without overt left heart failure and under haemodynamic surveillance, during the first two days of myocardial infarction. To achieve different states of hydration the patients were given i.v. furosemide, either 40 mg t.i.d. (high dose group—HDG) or 20 mg once daily (low dose group—LDG). Effects of altered body position and the respective furosemide injections, were evaluated on both days.Mean 24‐h‐diuresis was 3·9 1 in the HDG and 2·5 I in the LDG. After 24 h mean pulmonary arterial diastolic pressure had decreased by 30% in the HDG but remained almost unchanged in the LDG. By then mean basal TEI was increased only in the HDG, by 17% at 1 kHz and 13% at 100 kHz. On Day 1, within one hour after furosemide, TEI increased temporarily by 3–5%, at both frequencies and in both groups. On Day 2, this short‐term increase was similar in the LDG at both frequencies and in the HDG at 100 kHz, but not at 1 kHz, consistent with a major extracellular fluid loss in the HDG. TEI at 1 and 100 kHz may thus reflect extracellular and total thoracic fluid, respectively.
Insulin sensitivity in patients with arterial insufficiency. Re‐evaluation with the Multilevel Glucose Clamp Technique
Authors: Lundgren F. , Lundholm K. , Ekroth R. , Holm J. , Scherstén T. 
Published: April 2008

Summary. Previous studies have claimed that changes in insulin and glucose metabolism in patients with peripheral arterial insufficiency indicate an increased sensitivity to insulin for glucose uptake. We have re‐evaluated this concept in 11 patients with intermittent claudication and 11 matched controls with a multilevel euglycaemic glucose clamp technique. The groups were matched for age, sex and body composition but not completely for smoking habits and physical fitness. Although the control group had a normal physical fitness the patients had 40% lower maximal exercising capacity. The patients' maximal walking capacity was 186 ± 27 m evaluated on a treadmill. No patient with ischaemic ulcers or rest pain were included. The euglycaemic glucose clamp was performed at five insulin plateau levels (70, 110, 190, 590 and 1440 mU/l) of one h duration each and whole body glucose uptake during the last 20 min was calculated. No differences in maximal glucose uptake (Vmax) or insulin level for half maximal glucose uptake (Km) between the groups were observed. The concentration or the magnitude of the decrease in arterial FFA levels did not differ significantly between the groups at any physiological insulin level.This study can not confirm previously described changes in insulin sensitivity in patients with arterial insufficiency. Although the discrepancy between present and previous results remains unclear it may reflect the combined effects of different methods used, including the selection of reference patients, rather than an increased insulin sensitivity in patients with arterial insufficiency. This study suggests that previous conclusions based on glucose tolerance tests should be interpreted with caution.
Non‐invasive evaluation of the long‐term results of coarctectomy in childhood
Authors: Wallentin I. , Hanson E. , Eriksson B. O. 
Published: April 2008

Summary. Nineteen young men operated upon for coarctation of the aorta in childhood were studied with pulse tracings from the femoral and carotid arteries and echocardiographic examination of the heart with estimation of the degree of hypertrophy and valve anomalies. The results were compared with intra‐arterial blood‐pressure measurements and angiographically measured width of the aortic anastomosis.Patients with markedly distorted pulse curves had the narrowest anastomoses although no uniform pattern could be detected. Although one of the selection criteria was ‘no other known cardiovascular malformation’, only three of the patients had completely normal aortic and mitral valves. Nine of the patients had left ventricular hypertrophy but the degree of hypertrophy could not be correlated to the degree of arterial hypertension.The importance of long‐term follow‐up of these patients, who in spite of surgery have a remaining cardiovascular excess mortality, is emphasized. Pulse tracings and echocardiography seem to be of value for this purpose.
Potassium and myoglobin release and ST and QRS vector changes during acute myocardial infarction
Authors: Sylvén C. , Sederholm M. 
Published: April 2008

Summary. Thirty‐three consecutive patients aged 39 to 77 years with signs of myocardial infarction with a duration of symptoms of less than 4 h took part in the study. Serial blood sampling was done for the determination of myoglobin (MG), creatine‐kinase (CK) and potassium (K). Continuous vectorcardiography was monitored.Peak rates of K and MG release occurred 7·0 ± 3·7 and 6·5 ± 3·9 hours, respectively, after the onset of symptoms not different from the end of ST vector change that occurred after 7·6 ± 2·8 h. Following the end of ST vector change there was a 4‐hour delay until the end of QRS vector change and another 8‐hour delay to the end of MG release occurring about 20 h after the onset of symptoms. At the time for peak rate of MG release 48 ± 17% of total MG release had occurred.In conclusion, the physiologically different indicators of myocardial damage showed signs of maximum release within the same time range, 6–8 h after the onset symptoms and 8–10 h before signs of completed infarction.
The effect of exercise on platelet beta‐adrenoceptor function and platelet aggregation in healthy human volunteers
Authors: Winther K. , Trap‐Jensen J. 
Published: April 2008

Summary. Plasma levels of adrenaline and noradrenaline, platelet cyclic‐AMP (cAMP) content, platelet aggregation, platelet release of beta‐thromboglobulin, and platelet factor 4 and serum content of thromboxane B2(TXB2) and 6‐keto‐PGF1α were measured in 12 healthy male volunteers (age 38–72, mean 54·2 years) who were tested at rest and immediately after five min light cycle exercise.The plasma levels of adrenaline and noradrenaline increased significantly after exercise (P<0·01). The platelet cAMP level was not changed by exercise. The functional capacity of platelet beta‐adrenoceptors, determined as cAMP production after beta‐adrenoceptor stimulation in vitro, decreased highly significantly after exercise in all 12 volunteers (P<0·01). No alteration was observed in platelet aggregation induced by adrenaline or in platelet release of beta‐thromboglobulin or platelet factor 4. No change was observed in the serum levels of TXB2 and 6‐keto‐PGF1α.In conclusion: light cycle exercise results in a decreased functional capacity of platelet beta‐adrenoceptors, but has no effect on platelet aggregation or platelet release. This might indicate a concomitant and equal decreased functional capacity of platelet alpha‐adrenoceptors.
Angiotensin II attenuates reflex decrease in heart rate and sympathetic activity in man
Authors: Sander‐Jensen K. , Secher N. H. , Astrup A. , Christensen N. J. , Damkjær‐Nielsen M. , Giese J. , Warberg J. , Bie P. 
Published: April 2008

Summary. Circulatory variables and hormone concentrations in arterial plasma were measured in six normal subjects during angiotensin II (ANG II) step‐up infusion of 0·25 and 1·00 ng kg‐1× min. During the 1·00 ng kg‐1× min infusion ANG II plasma concentrations increased from 11 ± 2 to 48 ± 6 pg ml‐1; i.e., similar to those obtained during acute hypotensive hypovolemia in man. Mean arterial pressure increased (P<0·05) from a resting value of 89±3 to 97±5 mmHg. Heart rate and catecholamine concentrations did not change. Plasma aldosterone increased (P<0·05) from 36 ± 4 to 77 ± 10 pg ml‐1 during the infusion. Plasma concentrations of vasopressin, adrenalin and pancreatic polypeptide did not change during the investigation. During the 0·25 and 1·00 ng kg‐1× min infusion subcutaneous blood flow decreased (P= 0·06) to 67 ±20 and 66 ±26%, respectively, of control.It is concluded that: (1) ANG II in physiological doses in man may augment the sympathetic activity on the circulatory system since compensatory decreases in heart rate or in plasma catecholamines were not observed during the increased arterial pressure; (2) ANG II does not induce a general decrease in vagal tone as plasma pancreatic polypeptide concentrations were unchanged; (3) the obtained plasma concentrations of ANG II do not stimulate the release of vasopressin to plasma; and (4) the threshold for reducing the subcutaneous blood flow is reached within relatively small increments in plasma ANG II.
Left ventricular volumes during graded upright exercise in healthy untrained subjects
Authors: Kelbæk H. , Christensen N. J. , Godtfredsen J. 
Published: April 2008

Summary. Left ventricular (LV) volume changes were studied by radionuclide cardiography at rest and during graded upright bicycle exercise in seven healthy untrained men aged 21–30 years. The exercise‐induced changes in LV volumes were most pronounced during mild exercise: from rest to 25% submaximal exercise stroke volume increased by 26% and LV ejection fraction from 0·60 to 0·69 (both P<0·01), whereas further increments of the work load resulted in only small changes of these variables. LV end‐diastolic volume increased initially by 10% (P<0·05) but returned to baseline values at higher work loads, whilst a rather constant decrease was recorded in LV end‐systolic volume during increasing exercise loads.Changes in plasma catecholamine levels were most pronounced at the high work loads, indicating that these hormones are not directly contributing to the LV volume changes.
Leg exchange of amino acids during exercise in patients with arterial insufficiency
Authors: Lundgren F. , Zachrisson H. , Emery P. , Bylund‐Fellenius A.‐C. , Elander A. , Bennegård K. , Scherstén T. , Lundholm K. 
Published: April 2008

SummaryIntermittent claudication is associated with adaptation in muscle metabolism. This study has evaluated the metabolism of amino acids at rest and during non‐steady state exercise in patients with arterial insufficiency of at least six months duration in comparison with matched control individuals. The exchange of amino acids were measured during two periods of acute exercise; one initial exercise period with a standardized work load and exercise time and a second exercise period which continued until further exercise was impossible due to pain in the patients and exhaustion in the controls.The maximum blood flow was reduced by 40% in the patients but the maximum oxygen uptake per unit power developed was almost the same in patients and controls. The patients had significantly lower concentrations of glutamine, lysine and taurine at rest compared with the controls. The exchange of amino acids across the resting leg did not differ between the two groups. Exercise increased the efflux of amino acids in both patients and controls. The efflux of glutamine (896 ± 205 vs. 48 ± 359 nmol/100 ml/min/watt) was higher in the patients compared to the controls at the first exercise period with inverse changes in the opposite direction of asparagine (149 ± 105 vs. 799 ± 121 and 27 ± 70 vs. 633 ± 334 nmol/100 ml/min/watt at the first and second exercise, respectively. Alanine release did not differ between the groups. The complementary patterns of glutamine and asparagine during hypoxic exercise in the patients may reflect the fact that these amino acids share a common carrier system. The similarity in the efflux of non‐metabolized amino acids, such as methionine, phenylalanine, tyrosine and 3‐methylhistidine, indicated that muscle hypoxia in claudication patients did not promote net degradation of either globular or myofibrillar proteins, although exercise increased the efflux of 3‐methylhistidine three‐ to fourfold in both patients and control individuals (from 1 ± 0·4 to 4 ± 1·8 and from 0 ± 0·7 to 6 ± 2·5 nmol/100 ml/min/watt, respectively). The exercise‐induced alterations in leg exchange of amino acids were restored within 10–20 min following exercise regardless of hypoxia.The results demonstrate that patients with arterial insufficiency have altered intermediary metabolism of amino acids during exercise. However, muscle hypoxia in such patients does not seem to promote a negative protein balance or induce serious alterations in cell membrane integrity.
Cardiovascular effects of positive end‐expiratory pressure during acute left ventricular failure in dogs
Authors: Hevrøy O. , Reikerås O. , Grundnes O. , Mjøs O. D. 
Published: April 2008

SummaryHaemodynamic and metabolic effects of ventilation with positive end‐expiratory pressure (PEEP) were studied in closed‐chest dogs anaesthetized with sodium pentobarbital during normal cardiac function and during acute left ventricular (LV) failure. LV failure was induced by embolizing the left coronary bed with 50 μm plastic microspheres causing a marked depression of LV function. End‐expiratory pressure was set to 0, 5, 10 and 15 cm H2O both before and after coronary embolization. During normal cardiac function PEEP above 5 cm H2O depressed cardiac output (CO) significantly. However, following coronary embolization after which LV function was seriously impaired, CO was maintained as PEEP was applied. This is attributed to reduced sensitivity to the LV pre‐load reductions induced by PEEP during LV failure. PEEP reduced MBF both during normal and impaired LV function. This did not result in ischaemic myocardial metabolism assessed by lactate extraction either in normal hearts or following coronary embolization. The reduced MBF was, however, associated with reduced MV̇O2 both during normal cardiac function and during LV failure. It is suggested that the reduced MBF is mainly due to reduced myocardial oxygen demand probably caused by reduced LV wall tension during PEEP ventilation.