Search PubMed⌕ Search

Biomedical subjects

E Eldrup

Publications and source records attributed to E Eldrup.

35 records · Page 2Linked to original sources
PubMed1989

Plasma dihydroxyphenylalanine (DOPA) is independent of sympathetic activity in humans.

To clarify the origin of plasma DOPA (3,4-Dihydroxyphenylalanine), the relationship between plasma DOPA and acute or chronic changes in sympathetic activity has been studied. Plasma DOPA and noradrenaline (NA) concentrations were measured by reverse-phase high-performance liquid chromatography with electrochemical detection. Administration of clonidine to healthy men decreased plasma NE markedly compared to no drug. Plasma DOPA decreased slightly but significantly with time, but values were identical after clonidine compared to no drug. Baseline plasma NE concentrations were significantly reduced in diabetic patients with autonomic neuropathy compared to diabetics without neuropathy, whereas baseline plasma DOPA concentrations were similar in the three groups investigated: 6.55 (5.03-7.26, median [interquartile range], n = 8) nmol l-1 in diabetics with neuropathy, 7.41 (5.79-7.97, n = 8) nmol l-1 in diabetics without neuropathy, and 6.85 (5.58-7.36, n = 8) nmol l-1 in controls. No relationship was obtained between baseline values of plasma NE and plasma DOPA. Plasma DOPA did not change in the upright position, whereas plasma NE increased significantly. Our results indicate that plasma DOPA is not related to sympathetic activity and may be of non-neuronal origin.

Adult↗
PubMed1989

Coronary risk factors, development of myocardial infarction, and plasma oestrogens: a prospective case-control study in men.

A number of studies have reported hyperoestrogenaemia in men surviving an acute myocardial infarction (AMI). This has led to speculations that hyperoestrogenaemia might be a coronary risk factor. It is not clear why plasma levels of oestrogens should be elevated in coronary heart disease. To ascertain whether hyperoestrogenaemia might be present before the onset of a myocardial infarction, we performed a prospective study in 252 men above the age of forty who within the following 5 years suffered an AMI and, as controls, 526 men matched for age and coronary risk factors and 329 randomly selected men. Mean plasma concentrations of oestradiol and oestrone did not differ significantly between the groups. This suggests that hyperoestrogenaemia is not a coronary risk factor and thus, if present after the AMI, is more likely develop concurrently with the myocardial infarction.

Adult↗
PubMed1989

DOPA, norepinephrine, and dopamine in rat tissues: no effect of sympathectomy on muscle DOPA.

We studied the effect of unilateral sympathectomy on rat quadriceps and gastrocnemius muscle concentrations of endogenous dihydroxyphenylalanine (DOPA), dopamine (DA), and norepinephrine (NE) and assessed the relationships between these catecholamines in several rat tissues. Catecholamines were measured by reverse-phase high-performance liquid chromatography with electrochemical detection. Sympathectomy decreased NE and DA concentrations of muscles to approximately 10% of control values, whereas the DOPA concentration tended to increase. Relatively high concentrations of DOPA were found in the gastrointestinal tract, kidney, and spleen. No correlations were obtained between the tissue concentration of DOPA and NE. A DA-to-NE ratio approximately 1% was observed in liver, muscle, pancreas, spleen, and heart, whereas we found exponentially increasing DA values with increasing NE concentration in tissues obtained from stomach, small and large intestine, kidney, and lung. In conclusion, endogenous DOPA in muscle tissue is not located in sympathetic nerve terminals but probably in muscle cells. DA concentrations in the gastrointestinal tract and in the kidneys were greater than could be ascribed to its role as a precursor in the biosynthesis of NE.

Animals↗
PubMed1988

The effect of MPTP on uridine uptake in murine nerve cells.

Sixty, 3-month-old, male Theiler mice were injected with 1 mg 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) each i.p. Six groups of 5 animals each were then injected with 0.25 mCi [5-H3]uridine i.v. at intervals of 6h, 1,2,5,7 and 9 weeks after MPTP injection and each group was killed 1 h after uridine injection. Microautoradiograms were performed and the grain number determined in nerve cell nuclei in the striatum, substantia nigra and cerebral cortex. An initial increase in uridine uptake was found in substantia nigra, followed by a decrease during the following 9 weeks. A decrease in uptake occurred in the striatum from weeks 5-9, but without any initial increase. An increase in uptake was observed in the cortex 2 weeks after MPTP injection. Thus, in mice, a single injection of MPTP has a significantly prolonged effect upon the basic metabolic process (RNA synthesis) in substantia nigra and striatum. Selegiline, which causes a significant decrease in uridine uptake, also protects nerve cells from the effect of MPTP. The amount of dopamine in striatum and substantia nigra following MPTP did not change significantly during the 9 weeks. However, the amount of dihydroxyphenylalanine (DOPA) increased in both these areas during this period.

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine↗
PubMed1988

Differential effects of timolol and metoprolol on platelet function at rest and during exercise.

Ten male patients suffering from stable angina pectoris were studied at rest and immediately after exercise during treatment either with timolol (a non-selective beta-blocker) or with metoprolol (a beta 1-selective blocker). Timolol induced a significant increase in platelet aggregation and a reduction in platelet cyclic AMP, and it also raised the plasma adrenaline at rest and during exercise as compared to the pre-treatment level. Metoprolol had none of these effects. Prior to medication and during metoprolol treatment, exercise led to an increase in the peripheral platelet count, whereas timolol was associated with a reduction of platelets during physical effort. Neither drug affected platelet thromboxane B2 at rest. During exercise, its level was not affected in the pre-treatment period or during metoprolol treatment but it was sharply increased by timolol therapy.

Adrenergic beta-Antagonists↗
PubMed1988

Plasma free and sulfoconjugated dopamine in man: relationship to sympathetic activity, adrenal function and meals.

Peripheral venous plasma free and sulfoconjugated catecholamines, dopamine (DA), noradrenaline (NA) and adrenaline (A) were measured in normal men (n = 6-7) during conditions significantly altering adrenal and sympathoadrenal function (influence of corticotropin, furosemide, hypoglycaemia and clonidine), after dopamine receptor blockade with metoclopramide and after meals. Median (range) basal plasma free DA concentration was 0.13 (0-0.72) nmol/l and median (range) basal plasma conjugated DA concentration was 15.16 (6.34-45.03) nmol/l. Meals increased plasma sulfoconjugated DA markedly from a median value of 14.97 nmol/l during fasting experiments to a median value of 33.01 nmol/l (p less than 0.05). Plasma free DA did not change in the meal experiments. No changes in plasma DA were observed after administration of corticotropin, furosemide, clonidine, and metoclopramide or during hypoglycaemia. The results suggest that plasma sulfoconjugated DA is derived at least in part from the gastrointestinal tract and not from the sympathoadrenomedullary system as hitherto proposed.

Adrenal Glands↗
PubMed1987

Plasma sex hormones and ischemic heart disease.

The reason why men have a higher incidence of ischemic heart disease than women, and women rarely develop ischemic heart disease before the menopause, is not known. However, elevated plasma estradiol and estrone concentrations have been found in men surviving myocardial infarction. Hence, hyperestrogenemia has been suggested as a coronary risk factor. To assess this theory we review the literature on sex steroid production, the relationship between established coronary risk factors and plasma sex hormones, as well as results from clinical trials in which estrogens have been administered to men and women. Other possible explanations why plasma estradiol levels are elevated in male survivors of myocardial infarction are discussed. Based on earlier and recent evidence, it is hypothesized that the elevated plasma estradiol concentration found in men surviving myocardial infarction is due to either the myocardial infarction itself or established risk factors such as smoking or hypertension.

Androstenedione↗
PubMed1987

Dopaminergic regulation of gonadotropin levels and pulsatility in normal women.

This study was done to define the concentration of dopamine (DA) that inhibits gonadotropin secretion and to study the effect of DA D-2 receptor blockade during the infusions. Normal women received 5-hour infusions of either glucose (n = 14) or DA at rates of 0.04 (n = 6), 0.4 (n = 6), and 4.0 micrograms/kg X minute (n = 9). After 3 hours, metoclopramide (MTC) was administered. Mean serum luteinizing hormone (LH) concentration declined during 0.4 (P less than 0.01) and 4.0 micrograms/kg X minute (P less than 0.05) infusion doses of DA. This effect of DA was not consistently (P greater than 0.05) antagonized by MTC. Six women received DA (4.0 micrograms/kg X minute) or glucose for 18 hours. After 17 hours, MTC was given. Blood samples were collected every 10 minutes during the last 8 hours. No significant effect on LH pulse frequency and pulse amplitude was observed (P greater than 0.05). A marked (P less than 0.01) rise in LH occurred after MTC administration. The authors conclude that (1) physiologic doses of DA may inhibit LH secretion with only little, if any, effect on the pulsatile release; and (2) low-affinity DA receptors responsive to DA D-2 antagonists may regulate LH secretion.

Adult↗
PubMed1986

Streptokinase therapy in the routine management of deep venous thrombosis in the lower extremities. A retrospective study of phlebographic results and therapeutic complications.

One hundred and eight patients with phlebographically verified deep venous thrombosis were treated with streptokinase. Total or partial thrombolysis was phlebographically demonstrated in 60 patients (55.6%). Three patients died during treatment, all from pulmonary embolism. Six patients developed clinical signs suggestive of pulmonary embolism. In 16 patients (14.8%), major bleeding complicated the treatment. One patient had anaphylactic shock, while various allergic reactions were recorded in 22. Streptokinase therapy in the routine management of deep venous thrombosis carries an acceptable efficacy and safety similar to what has been achieved under research conditions.

Adolescent↗
PubMed1985

Bilateral subdural haematoma demonstrated at scintigraphy of the brain.

Bilateral subdural haematoma is not a rare disorder, but only a few cases diagnosed at brain scintigraphy have been reported. Bilateral subdural haematoma was demonstrated at scintigraphy in a 66-year-old man. Subsequent computerized-tomography scanning of the brain also demonstrated the lesion. After bilateral burr-hole aspiration, the patient made a good recovery.

Aged↗
PubMed1982

Effects of a small serosal hydrostatic pressure on sodium and water transport and morphology in rabbit gall-bladder.

1. In order to investigate the mechanism of serosal pressure-induced inhibition of isosmotic fluid transport, the effect of 4.5 cm water serosal pressure on spontaneous water transfer (J(v)) in rabbit gall-bladders was measured (in the presence of a supporting soft nylon net on the mucosal side) in a modified Ussing chamber. This allowed unidirectional Na(+) fluxes ([Formula: see text] and [Formula: see text]), transepithelial potential difference and resistance (R(t)) to be measured simultaneously. The effects of the serosal pressure were also investigated by light and electron microscopy.2. During pressure application, R(t) increased due to a covering effect of the mucosal support. The serosal pressure caused a parallel decrease in J(v) and net Na(+) transport ([Formula: see text]) across the free epithelial surface of 80-85%. About 85% of the decrease in [Formula: see text] was due to a decrease in [Formula: see text].3. After inhibition of 93% of fluid absorption by serosal 10(-3)M-ouabain, pressure-induced change in J(v) was only 8% of the spontaneous fluid transport rate.4. Control Na(+) flux ratio ([Formula: see text]) was 3.5. The pressure-induced increase in steady-state [Formula: see text] of 30-35% therefore contributed little to the decrease in [Formula: see text]. Further, this increase in [Formula: see text] was completely prevented by mucosal 10(-3) M-amiloride.5. All pressure-induced effects on transport and electrical parameters were reversible.6. The light microscopical and scanning electron microscopical results showed that half of the epithelial surface was covered by the nylon net following serosal pressure application. Ruptures in the epithelium were not seen. Thin section and freeze fracture electron microscopy demonstrated continuous, well developed tight junctions both in control and experimental condition.7. It is concluded that a serosal pressure of only 4.5 cm water causes inhibition of a cellular active Na(+) and water transport with only minimal, if any, contribution from paracellular filtration. This would seem incompatible with the concept that an active ion transport mechanism localized in the basolateral cell membrane is responsible for transepithelial fluid transport. The possibility of a mechanical fluid transport mechanism via elements of a tubulo-cisternal endoplasmic reticulum is raised.

Amiloride↗
PubMed1980

Possible epithelial sodium channels visualized by freeze-fracture.

The coprodeum is a very efficient Na+-retaining epithelium. Coprodeum from birds on a high Na+ diet has virtually no ion transport, while an Amiloride-sensitive Na+ absorption of 10--12 mu equiv . cm-2 . h-1 is induced in the coprodeal epithelium from birds on a low Na+ diet. Both measurements of the Na+ influx and Na+-diffusion potentials across the luminal cell membrane have revealed a selective opening of this membrane to Na+ in birds on a low Na+ diet. Freeze-fracture P faces of the luminal membrane in coprodea taken from birds on a low Na+ diet have rod-shaped particles, 100 x 240 A, in more than 20% of the principal cells. Rod-shaped particles appear in less than 1% of these cells in coprodea from high Na+-diet birds. Thus a low Na+ diet induces rod-shaped particles in the luminal cell membrane of the hen coprodeum. These new particles may function as Na+-channels mediating the increased Na+-influx across the apical cell membrane.

Animals↗