Biomedical subjects

I L Kanstrup

Publications and source records attributed to I L Kanstrup.

At least 55 records · Page 3Linked to original sources

PubMed1994

Postoperative Tc-scintimetry in femoral neck fracture. A prospective study of 46 cases.

13 men and 33 women with 8 undisplaced and 38 displaced fractures of the femoral neck treated with internal fixation were included in a prospective study of Tc-scintimetry performed early (1-3 weeks), as well as after 2 and 12 months. 9 fractures redisplaced and 5 had late segmental collapse. Healing complications were associated with decreased uptake in early and 2-month scintimetry, but the specificity was only 50 percent. With normal or increased uptake, uncomplicated healing of the fracture was predictable with 90-100 percent sensitivity.

Aged↗

PubMed1993

Dopamine, dobutamine, and dopexamine. A comparison of renal effects in unanesthetized human volunteers.

BACKGROUND: Recently, dopexamine (DX), which acts via adrenergic beta 2 and dopaminergic DA1 receptors, has been introduced in the treatment of low cardiac output states. However, the renal effects of DX have not been compared to those produced by equipotent inotropic doses of dopamine (DA), which predominantly stimulates DA1 and DA2 receptors, and of dobutamine (DB), which stimulates beta 1 but not DA receptors. The current study tested the null hypothesis that, with equal increases in cardiac output, DX, DA, and DB would have similar effects on renal function. METHODS: Each drug was given for 2 h on three different occasions to eight normal subjects in doses adjusted to produce a similar 30-35% increase in cardiac output. Effective renal plasma flow (ERPF) and glomerular filtration rate (GFR) were measured as renal clearances of 131I-hippuran and 99mTc-DTPA, respectively. Lithium clearance (CLi) was used as an index of proximal tubular outflow. RESULTS: Doses of DA, DX, and DB were 2.90 +/- 0.19, 1.00 +/- 0.02, and 4.92 +/- 0.40 microgram.kg-1.min-1, respectively. Dopamine and DX increased ERPF by 23% and 10%, respectively, whereas ERPF remained unchanged during DB. The increase in ERPF was smaller during DX compared with DA. The GFR remained unchanged during DA and DB, but increased during DX (7%). The CLi increased by 35% and 30% during DA and DX, respectively, but was not changed by DB. Calculated absolute proximal reabsorption rate (APR = GFR--CLi) decreased by 13% during DA, but remained unchanged during DB and DX. Dopamine increased sodium clearance (CNa) by 103%, but the changes during DX and DB were not significant. Only DA decreased fractional distal reabsorption (FDRNa = 1--CNa/CLi). CONCLUSIONS: The findings are consistent with a specific, renal-vasodilating effect of DA and DX. However, in the current doses, this effect of DX was of lesser magnitude compared with that of DA. Only DA significantly increased CNa, and the decreases in APR and FDRNa indicate that an effect on tubular reabsorption rate contributed to the natriuresis.

Adult↗

PubMed1993

Spleen emptying and venous hematocrit in humans during exercise.

The spleen may release pooled erythrocytes to the general circulation during strenuous conditions such as heavy exercise. Most of our knowledge of this reservoir function of the spleen derives from animal studies, and the splenic contribution to the circulating blood volume in humans has been regarded as unimportant. We recorded the erythrocyte content in the human spleen during graded bicycle exercise to maximal working capacity. In five normal adults 99mTc-labeled autologous erythrocytes were injected intravenously, and the subjects were placed on bicycles with the back against a gamma camera focusing on the spleen. During increasing exercise the splenic erythrocyte content decreased linearly, and at maximal work load it had been reduced to a mean of 34.2% (range 44-26%) of the initial count rate at supine rest. Concomitantly norepinephrine and epinephrine in plasma increased gradually, whereas neuropeptide Y increased only at maximal exercise. A rise in hematocrit from a mean of 44.6 to 48 was observed, but the autotransfusion of erythrocytes from the spleen only partly explains the rise in hematocrit during physical activity.

Adult↗

PubMed1993

Renal hemodynamics, tubular function, and response to low-dose dopamine during acute hypoxia in humans.

Renal function was investigated in eight normal subjects before and during infusion of dopamine (3 micrograms.kg-1 x min-1) at sea level (SL) and at high altitude (HA, 4,350 m). Lithium clearance (CLi) was used as an index of proximal tubular outflow. HA significantly increased arterial pressure, heart rate, and plasma norepinephrine. Effective renal plasma flow (ERPF) decreased at HA by 10% (P < 0.05), but glomerular filtration rate (GFR), CLi, sodium clearance (CNa), and urine flow remained unchanged compared with SL. Dopamine at SL and HA increased ERPF by 47% (P < 0.001) and 30% (P < 0.01), respectively, but the increase at HA was smaller than that at SL (P < 0.05). Dopamine increased GFR only at SL. CLi and CNa increased by 29% (P < 0.001) and 108% (P < 0.001) at SL and by 23% (P < 0.01) and 108% (P < 0.001) at HA. Whereas dopamine at SL increased urine flow by 46% (P < 0.01), this response was abolished at HA, and free water clearance decreased (P < 0.05). The decreased ERPF at HA suggests a constriction of the renal arterioles secondary to increased adrenergic nervous activity. Although the effect of dopamine on ERPF was attenuated in hypoxia, dopamine-induced increases in CLi and CNa remained unaltered, suggesting that natriuresis in both environments was secondary to an increased outflow from the proximal tubules. The absence of a diuretic response to dopamine at HA seemed to be caused by an effect on distal tubular function.

Acute Disease↗

PubMed1992

Age-related changes of exercise-induced plasma catecholamines and neuropeptide Y responses in normal human subjects.

Age-related plasma noradrenaline and neuropeptide Y were evaluated in seven young (mean +/- SD, 28 +/- 3 years) and seven elderly (64 +/- 8 years) normal subjects during rest and different work loads on a cycle ergometer. In the supine and the sitting position plasma noradrenaline and neuropeptide Y were almost identical in the two groups. Plasma neuropeptide Y did not increase during exercise at 100 W for 15 min. At this load plasma noradrenaline levels were higher in the older subjects (mean +/- SEM, 0.97 +/- 0.12 vs. 0.60 +/- 0.09 ng ml-1). There was a significant correlation between plasma noradrenaline and the relative work load at 100 W (r = 0.794, P = 0.0007). At 75% of maximal work load plasma noradrenaline and neuropeptide Y were higher in the young group (1.84 +/- 0.16 vs. 1.26 +/- 0.13 ng ml-1 (noradrenaline) and 38 +/- 4 vs. 22 +/- 5 pmol l-1 (neuropeptide Y)). In the elderly group plasma neuropeptide Y did not increase during exercise and showed a tendency to fall below basal level 5 min post-exercise. It is concluded, that plasma noradrenaline does not increase more in older subjects during exercise when correcting for the generally lower physical fitness in this group compared to younger subjects, and that plasma neuropeptide Y does not increase during exercise in older subjects, suggesting an age-reduced capacity in this system.

Adult↗

PubMed1992

Acute plasma expansion: left ventricular hemodynamics and endocrine function during exercise.

In 11 healthy subjects (8 males and 3 females, age 21-59 yr) left ventricular end-diastolic (LVEDV) and end-systolic (LVESV) volumes were measured in the supine position by isotope cardiography at rest and during two submaximal one-legged exercise loads before and 1 h after acute plasma expansion (PE) by use of a 6% dextran solution (500-750 ml). After PE, blood volume increased from 5.22 +/- 0.92 to 5.71 +/- 1.02 (SD) liters (P < 0.01). At rest, cardiac output increased 30% (5.3 +/- 1.0 to 6.9 +/- 1.6 l/min; P < 0.01), stroke volume increased from 90 +/- 20 to 100 +/- 28 ml (P < 0.05), and LVEDV increased from 134 +/- 29 to 142 +/- 40 ml (NS). LVESV was unchanged (44 +/- 11 and 42 +/- 14 ml). Heart rate rose from 60 +/- 7 to 71 +/- 10 beats/min (P < 0.01). The cardiac preload [central venous pressure (CVP)] was insignificantly elevated (4.9 +/- 2.1 and 5.3 +/- 3.0 mmHg); systemic vascular resistance and arterial pressures were significantly reduced (mean pressure fell from 91 +/- 11 to 85 +/- 11 mmHg, P < 0.01). Left ventricular peak filling and peak ejection rates both increased (19 and 14%, respectively; P < 0.05). During exercise, cardiac output remained elevated after PE compared with the control situation, predominantly due to a 10- to 14-ml rise in stroke volume caused by an increased LVEDV, whereas LVESV was unchanged. CVP increased after PE by 2.1 and 3.0 mmHg, respectively (P < 0.05).2+ remained unchanged during exercise compared with rest after PE in

Adult↗

PubMed1992

Effects of acute hypoxia on renal and endocrine function at rest and during graded exercise in hydrated subjects.

Renal effects of altitude hypoxia are unclear. Renal and hormonal function was investigated in eight males at rest and during graded exercise at sea level (SL) and 48 h after rapid ascent to 4,350 m (HA). HA did not change resting values of effective renal plasma flow (ERPF), glomerular filtration rate (GFR), sodium clearance (CNa), urine flow, or lithium clearance (CLi), which was used as an index of proximal tubular outflow. At rest, HA increased plasma norepinephrine concentration and decreased plasma concentrations of renin and aldosterone. Exercise decreased ERPF similarly in both environments. Normoxic exercise progressively reduced GFR, but at HA GFR only decreased during heavy exercise. This resulted in a higher filtration fraction during light and moderate hypoxic exercise. However, calculated absolute proximal reabsorption rate (GFR-CLi) at HA was higher during low-intensity exercise, and there were no significant differences between exercise-induced decreases in CLi, CNa, and urine flow at HA compared with SL. Exercise gradually increased plasma norepinephrine, but values were higher at HA during light and moderate exercise. The small changes in the renal response to low-intensity hypoxic exercise may be secondary to increased adrenosympathetic activity. However, antidiuretic and antinatriuretic effects of exercise were maintained in hypoxia and in both environments seemed to be the consequence of decreased proximal tubular outflow. The results demonstrate that renal glomerular and tubular function is well preserved in acute hypoxia despite marked hormonal changes.

Adult↗

PubMed1992

Myocardial perfusion at fatal infarction: location and size of scintigraphic defects.

In a consecutive study of myocardial scintigraphy in acute ischemic syndrome, four patients had 99mTc-hexamibi injected intravenously before they developed fatal cardiogenic shock. Planar scintigraphy was performed after death. Slices of the hearts after autopsy were analyzed for scintigraphic and pathoanatomic abnormalities. Location of perfusion defects in planar views of the heart was in good agreement with the scintigraphied, sliced sections. The extent of infarction judged from inspection and formasan staining was much smaller (7%-40% and 6%-43% of the total slice area) than found at scintigraphy, where 83%-92% of the myocardium showed ischemia as defined by a 99mTc-hexamibi uptake below an arbitrary limit on half maximum uptake. Myocardial hypoperfusion might thus aggravate the functional impairment at myocardial infarction and lead to cardiogenic shock.

Aged↗

PubMed1991

Menstrual patterns in Danish elite swimmers.

Questionnaires were given to 140 female elite swimmers from the highest ranking division in the Danish Swimming Association inquiring about their menstrual history. Eighty-nine percent completed the questionnaires. We found a very low incidence of menstrual dysfunction (16%) compared to other groups of endurance trained females. Hard physical endurance training did not seem to delay the onset of menarche among swimmers. Furthermore, no difference in adjusted body mass between a group with oligomenorrhoea and a normal menstruating group could be demonstrated. The study indicated that the influence of body mass or body fat content was a more important factor in menstrual function than the amount of training or psychological stress.

Adolescent↗

PubMed1991

Unchanged extraction of atrial natriuretic factor across the chronic ischemic human kidney.

The extractions of atrial natriuretic factor (EANF) and the glomerular filtration marker 51Cr-ethylenediamine tetraacetic acid (EEDTA) were determined before and after intravenous injection of furosemide across each of the two kidneys during renal vein catheterization in hypertensive patients with unilateral or bilateral renovascular disease. Before administration of furosemide, EANF was approximately 55% across both the more and the less affected kidney while EEDTA was significantly decreased across the more affected kidney. Significant lateralization of renin secretion to the more affected kidney was found, demonstrating an enhanced ipsilateral formation of renin. Administration of furosemide caused a significant decrease in EEDTA across the less affected kidney while the ipsilateral EANF did not change. Furosemide caused no change in EEDTA or EANF across the more affected kidney. No significant correlations were found between EANF and EEDTA. These results demonstrate that the extraction of ANF is unchanged across the chronic ischemic human kidney. Furthermore, in the single kidney, changes in EEDTA, as induced by furosemide, are not related to changes in ipsilateral EANF. Since the relation between simultaneously determined single kidney extractions of ANF and 51Cr-EDTA reflects the relation between the single kidney clearance of ANF and the ipsilateral glomerular filtration rate, our data indicate a dissociation between changes in the single kidney glomerular filtration rate and the ipsilateral total renal clearance of ANF.

Atrial Natriuretic Factor↗

PubMed1989

Atrial natriuretic factor: comparability of venous and arterial plasma measurements in man at rest and during exercise.

1. Simultaneously obtained arterial and venous plasma atrial natriuretic factor (ANF) concentrations were compared at supine rest and during graded dynamic leg exercise in 10 healthy male subjects (aged 33-51 years). 2. Arterial ANF concentrations ranged between 12 and 179 pg/ml and venous concentrations between 9 and 177 pg/ml. 3. A positive correlation between arterial and venous concentrations was found (r = 0.984). 4. Arterial ANF concentrations were higher than venous concentrations in all pairs of samples (n = 31), but the difference was small and changed little with exercise: the mean difference was 5 pg/ml at rest, 12 pg/ml during submaximal exercise and 6 pg/ml during maximal exercise. 5. The extraction ratios for ANF varied greatly, but were in general lower (P less than 0.05) during maximal exercise (median 0.07, range 0.01-0.32) than at rest (median 0.22, range 0.05-0.33). 6. It was concluded that the plasma ANF concentration in a peripheral arm vein is a good indicator of the systemic peptide concentration at rest as well as during dynamic leg exercise.

Adult↗

PubMed1987

Indocyanine green plasma clearance as a measure of changes in hepatic blood flow.

The results from simultaneous measurements of indocyanine green (ICG) plasma clearance and hepatic blood flow (HBF) in subjects without hepatic dysfunction during changes in HBF induced pharmacologically or by food stimulation, are reported. A linear relation is established between the relative changes in HBF and that of ICG clearance (r = 0.94), but the changes are not identical, and therefore the changes in HBF cannot be accurately predicted from that of ICG plasma clearance. The reason behind the lack of identity of the changes lies in the complicated kinetics of dye removal by the liver. The hepatic venous catheterization technique is the only method when physiologically correct values for hepatic blood flow or changes therein are wanted.

Adult↗

PubMed1984

Splanchnic and renal elimination and release of catecholamines in cirrhosis. Evidence of enhanced sympathetic nervous activity in patients with decompensated cirrhosis.

Plasma noradrenaline (NA) and adrenaline (A) concentrations were determined in different vascular areas in 32 patients with cirrhosis and in nine controls during a right sided heart, liver, and renal vein catheterisation. The patients were divided into four groups: (I) Compensated (without ascites); (II) Recompensated on diuretic treatment because of former ascites; (III) Decompensated (with ascites) without treatment and (IV) Decompensated on diuretic treatment. Median arterial noradrenaline concentrations were 1.48, 1.07, 2.66, 4.14 and 2.50 nmol/l in controls, group I, II, III, and IV, respectively, the three last mentioned values being significantly raised (p less than 0.01). Median arterial adrenaline concentrations were not significantly increased. In patients arterial-hepatic venous extraction ratios of noradrenaline and adrenaline were on the average 25% (p less than 0.01) and 20% (p less than 0.02) less than those of the controls, indicating a slightly reduced splanchnic elimination of catecholamines in cirrhoses. In controls and group I significant renal venous-arterial noradrenaline differences were absent (0.00 and 0.03 nmol/l) while renal venous-arterial noradrenaline differences were significantly increased in groups II, III and IV (0.47, 0.53 and 0.68 nmol/l, p less than 0.01), indicating a significant net release of noradrenaline from the kidneys in recompensated and decompensated patients. Renal extraction of adrenaline was normal. In conclusion, increased arterial noradrenaline in decompensated and recompensated cirrhosis is only to a limited extent owing to reduced net splanchnic elimination. More likely the increase is caused by release of noradrenaline from the kidneys and possibly other organs indicating enhanced sympathetic nervous tone in these conditions.

Adult↗

PubMed1984

Blood volume and hemoglobin concentration as determinants of maximal aerobic power.

Changes in blood volume (BV) and hemoglobin concentration ( [Hb] ) were induced in five healthy young men. After acute hypovolemic anemia was achieved by blood withdrawal, VO2max values decreased, while the same [Hb] due to acute plasma volume expansion (6% dextran) did not alter VO2max. After reinfusion of red blood cells, leading to hypervolemia and increased [Hb], VO2max increased. Plasma volume expansion in this situation, leading to hypervolemia at normal [Hb], resulted in a slight reduction in VO2max, which, however, remained elevated (approximately 4%) above control values. Physical performance, measured as time to exhaustion, corresponded to the changes in VO2max except for the hypervolemic anemic situation, where it decreased. Changes in peak heart rate were inversely related to BV changes, but were also influenced by [Hb]. The results point to a significant influence of the total amount of Hb rather than the blood hemoglobin concentration for obtaining a high maximal aerobic power. Thus, a reduced [Hb], concomitantly with an elevated blood volume (plasma volume), may result in an unchanged VO2max, but reduced performance time.

Adult↗

PubMed1983

General and regional haemodynamic effects of intravenous ergotamine in man.

The effect of intravenous ergotamine on general (blood pressure and cardiac output) and regional (splanchnic, renal and muscular) haemodynamics was studied immediately and 3 h after administration in seven male volunteers. Also plasma catecholamines were determined. An increase in blood pressure with a peak just after administration was observed. The cardiac output was unchanged and the pressor effect of ergotamine was due to an increase in total peripheral resistance. Plasma noradrenaline decreased 65% at the peak of the pressor effect whereas plasma adrenaline was unchanged. Hepatic blood flow decreased 34% just after ergotamine administration and was normal after 3 h. Renal blood flow decreased by 29 and 19%. Calf blood flow was unchanged. These results suggest that different vascular beds in man react differently to ergotamine.

Adult↗

PubMed1982

Treatment of diabetic orthostatic hypotension with pindolol.

The hemodynamic variables, plasma noradrenaline and plasma renin concentrations were studied in a 57-year-old female with insulin-dependent diabetes of long-standing and orthostatic hypotension. For 6 months she had been bedridden because of severe orthostatic symptoms. Reflex responses in the heart rate and blood pressure during the Valsalva manoeuvre as well as beat-to-beat variations in heart rate were absent. Plasma noradrenaline concentrations were subnormal both in the supine and upright positions. After treatment with Pindolol 15 mg/day the patient was able to walk around and lead an almost normal life. The orthostatic symptoms recurred after withdrawal of therapy and disappeared on resumption of therapy. Arterial blood pressure measured intra-arterially decreased less in the up-right position during treatment with pindolol compared to that in the untreated condition. The heart rate did not change during treatment with Pindolol. Our findings suggest that Pindolol may be an important drug in the treatment of diabetic orthostatic hypotension.

Autonomic Nervous System Diseases↗

PubMed1982

Acute hypervolemia, cardiac performance, and aerobic power during exercise.

The relative importance of blood volume (BV) for the maximum aerobic power (VO2 max) was evaluated in healthy subjects by sequential measurements without intervention under two conditions: 1) after hemodilution with a plasma expander, thus increasing BV but keeping red cell mass constant and lowering hemoglobin concentration [Hb], and 2) after whole blood withdrawal, which restored BV to control conditions but reduced red cell mass and [Hb] to equal conditions under 1. After BV expansion (avg 700 ml), we found an unchanged VO2 max compared with control data despite lowered [Hb]. Cardiac output (Q) was increased after BV expansion at rest and during all exercise levels (maximum 27.4 and 29.5 l . min-1, respectively). Peak stroke volume was increased from 144 to 173 ml. Arterial blood pressures were either unchanged or lowered. In contrast, after blood letting to a similar [Hb], we found a significantly reduced VO2 max. These findings indicate a significant influence of the size of the blood volume on cardiac performance. The increased Qmax is discussed in relation to preload, inotropic state, heart rate, and afterload. Plasma volume expansion causes increased preload which may explain this primary effect on the central circulation (Frank-Starling effect).

Adult↗

PubMed1981

Cardiac output measured by acetylene rebreathing technique at rest and during exercise. Comparison of results obtained by various calculation procedures.

Cardiac output (Qc) was measured by a rebreathing technique, using acetylene and a mass-spectrometer for analyzing. In addition the rate of pulmonary uptake of O2 (VO2) during the rebreathing period and during a preceding steady-state period were determined. Measurements were made on 8 adult humans at rest and at different levels of exercise up to maximum at two occasions. The ratio (VO2 during steady-state/VO2 during rebreathing) was found to be significantly below 1 when the steady-state VO2 was below about 21 . min-1 and to be about 0.55 for subjects at rest. This indicates that VO2, and hence Qc, is increased by the rebreathing procedure when this involves deeper and more frequent respirations than those of the preceding period. Accordingly, when VO2 was below about 21 . min-1, the Qc value, calculated exclusively from acetylene concentrations recorded during rebreathing, was multiplied by the above-mentioned VO2-ratio. It is shown that this correcting procedure gives more reasonable values than those obtained by acetylene data alone. It is pointed out in what respects this correcting procedure of calculation deviates from that originally used by Grollman, and it is shown that there are only moderate differences between the results obtained by the two procedures.

Acetylene↗