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Biomedical subjects

L Simonsen

Publications and source records attributed to L Simonsen.

At least 91 records · Page 5Linked to original sources
PubMed1990

The effect of 0.5% ropivacaine on epidural blood flow.

Twenty patients scheduled for elective abdominal surgery received epidural analgesia with 20 ml 0.5% ropivacaine or 0.5% bupivacaine. Epidural blood flow was measured by an epidural 133Xe clearance technique on the day before surgery (no local anaesthetic) and again 1 h before surgery, 30 min after injection of the local anaesthetic during continuous infusion (8 ml/h). Median initial blood flow was 5.0 ml/min and 6.0 ml/min per 100 g tissue in patients receiving ropivacaine and bupivacaine, respectively. After epidural bupivacaine, blood flow increased in 8 of 10 patients to 6.9 ml/min per 100 g tissue (P less than 0.05) in contrast to a decrease in 9 of 10 patients to 3.3 ml/min per 100 g tissue after ropivacaine (P less than 0.05), (P less than 0.01 between groups). The median level of sensory analgesia was T3.5 and T4.5 in the ropivacaine and bupivacaine group, respectively (P greater than 0.05). The demonstrated vasoconstrictor effect of epidural ropivacaine may influence the duration of its local anaesthetic effect.

Adult↗
PubMed1990

Diet-induced changes in subcutaneous adipose tissue blood flow in man: effect of beta-adrenoceptor inhibition.

The effect of a carbohydrate-rich meal on subcutaneous adipose tissue blood flow was studied with and without continuous i.v. infusion of propranolol in healthy volunteers. The subcutaneous adipose tissue blood flow was measured with the 133Xe washout method in three different locations: the forearm, the thigh and the abdomen. The subjects were given a meal consisting of white bread, jam, honey and apple juice (about 2300 kJ). The meal induced a twofold increase in blood flow in the examined tissues. Propranolol abolished the flow increase in the thigh and the abdomen and reduced it in the forearm. This indicates that the mechanism for the flow increase is elicited by a stimulation of vascular beta-adrenoceptors in the subcutaneous adipose tissue, since the beta-adrenoceptor inhibition did not affect the overall metabolic and hormonal responses to the meal.

Adipose Tissue↗
PubMed1989

[Intermittent claudication--social aspects in young patients not undergoing surgical treatment].

A total of 107 patients suffering from intermittent claudication (CI) was studied after a mean observation time of 5.9 years. Thirty-one (29%) had died during the observation period. A questionnaire was sent to 76 patients and 78% replied. All patients were under 50 years of age at the first consultation. No patients had been operated upon. The ratio women:men was 1:1.3. 33% received disability pensions or some other kind of pensions. Fifty-eight had limited their spare-time activities because of CI. It is concluded that a close control and reconstructive arteria surgery must still be recommended when the working ability is threatened.

Adult↗
PubMed1989

Neurophysiological and behavioural effects of combined exposure to 2,5-hexanedione and acetone or ethanol in rats.

Rats were dosed with 2,5-hexanedione (2,5-HD), acetone, ethanol or combinations of these for 6 weeks. Nerve conduction velocity (NCV) was measured in the tails of the rats once a week from the third week of dosing. Behaviour was monitored during the whole experiment as performance on a rotarod, in 30 sec. sessions. 2,5-HD alone showed a significant effect on NCV and rotarod performance after 3 weeks of dosing. Acetone, but not ethanol, together with 2,5-HD had an additional significant effect on NCV and rotarod performance of the rats. This additional effect was seen from the 4th dosage week. The mechanism behind this effect is partly unknown.

Acetone↗
PubMed1989

Epinephrine mediates facultative carbohydrate-induced thermogenesis in human skeletal muscle.

The thermic effect of carbohydrate has a component mediated by the sympathoadrenal system but of unknown anatomical localization. We have studied the contribution of skeletal muscle to the thermic effect of a carbohydrate-rich natural meal (115 g of carbohydrate, approximately 80% of energy) by means of the forearm technique on two occasions, with and without intravenous beta-blockade with propranolol. The meal-induced thermogenesis was reduced from 9.6 to 7.1% by beta-blockade (P less than 0.04), the major difference was found 90 to 240 min after the meal. The postprandial increments in plasma glucose and lactate did not change by beta-blockade, but there was a trend toward a decreased insulin response (P = 0.06). The carbohydrate-induced increase in forearm oxygen consumption was reduced by 23% after beta-blockade (P less than 0.05), the entire difference being present 90-180 min postprandially and coinciding with the peak in arterial epinephrine. The present study provides evidence of a facultative thermogenic component in skeletal muscle, mediated by epinephrine via beta 2-adrenoreceptors. However, it also points to a nonmuscle component mediated through beta 1-adrenoceptors by norepinephrine released from the sympathetic nervous system. Consequently, the sympathoadrenal system seems to play a physiological role in the daily energy balance.

Adult↗
PubMed1989

Changes in pneumonectomy-space gas tensions.

The development of a simple and reliable method for measurement of the partial pressures of the atmospheric gases offers the possibility of both basic and clinical examination of the air in natural as well as pathological or iatrogenic cavities. From measurements in nine patients a plot of the changes in pO2 and pCO2 in the pneumonectomy space from the end of the thoracotomy to the establishment of equilibrium with the blood gases was made. pCO2 equilibrated faster than pO2 (6- and 50 h respectively). The equilibrium difference between arterial pO2 and pneumonectomy space pO2 was 6.5 kPa (2.5-12.3 kPa) and we propose that measuring this difference may be a sensitive method for the diagnosis of bronchopleural fistula. During the study period one of the patients developed a bronchopleural fistula. The suspicion was based on X-ray findings and was supported by gas analysis from the pneumonectomy space, and conclusively confirmed by bronchoscopy.

Adult↗
PubMed1989

Tachyphylaxis associated with repeated epidural injections of lidocaine is not related to changes in distribution or the rate of elimination from the epidural space.

The relationship between tachyphylaxis (measured as a decrease in the rate of regression of sensory levels of analgesia) during repeated epidural injections of lidocaine and both the distribution of lidocaine within the epidural space (as measured by spread of simultaneous injection of the tracer technetium-99m diethylenetriaminepentaacetate [99mTc-DTPA]) and elimination of lidocaine from the epidural space (as measured by serum concentrations of lidocaine) was investigated in 18 patients undergoing minor surgery during lumbar epidural analgesia. Twelve patients received four injections of 20 mL of 2% lidocaine at 2-hr intervals. Epidural distribution was assessed by injection of 99mTc-DTPA diluted in saline on the preoperative day and diluted in an equal volume of 2% lidocaine on the morning before surgery and again after the fourth injection of lidocaine 6 hr later. The distribution of 99mTc-DTPA in the epidural space was unchanged during the three measurements despite significant tachyphylaxis in both sensory analgesia and motor blockade (11 of 12 patients had sensory analgesia 2 hr after the first injection in contrast to only 3 of 12 patients during the third injection). In another six patients 20 mL of 2% lidocaine were injected three times at 2-hr intervals before surgery, with measurements of serum concentrations of lidocaine after the first and last injections. Despite tachyphylaxis (no patient had sensory analgesia 2 hr after the third injection), there was no difference in the rate of disappearance of lidocaine from the epidural space as assessed by plasma lidocaine concentration curves during the first and third injection (0.5 +/- 0.1 and 0.3 +/- 0.04 microgram.mL-1.min-1, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1988

Microvascular circulatory changes in the lower extremities after reconstructive vascular surgery for intermittent claudication.

We have studied the circulatory changes in the lower extremities after reconstructive vascular surgery in ten patients with intermittent claudication. The following examinations were carried out 3 days before, 3 days, and 28 days after the operation: measurement of ankle systolic blood pressure, calf plethysmography, resting calf muscle blood flow and resting subcutaneous foot blood flow. The vasoconstrictor response (veno-arteriolar reflex) was also assessed. On the night before the operation and on the 28th night after aorto-bifemoral bypass surgery, subcutaneous adipose tissue blood flow in the forefoot was measured during sleep. The ankle systolic blood pressure and the ankle index rose significantly. The former increased from 57 +/- 16.4 mmHg to 93 +/- 24.0 mmHg (mean +/- S.E.M.) and was still elevated on the 28th postoperative day. The total limb blood flow, the muscle blood flow and the blood flow in the subcutaneous tissue of the forefoot during daytime were unchanged. In contrast, the blood flow in the forefoot during sleep increased significantly from 3.5 +/- 1.63 ml x (min x 100 g)-1 to 5.2 +/- 2.14 ml x (min x 100 g)-1 (mean +/- S.E.M.) on the 28th night. The vasoconstrictor response was potentiated, and increased from 27% before the operation to 45% on the third postoperative day. This change was maintained 28 days postoperatively. In conclusion the increase in arterial blood pressure was only reflected in the vasoconstrictor response which had returned to normal by the third postoperative day and nocturnal blood flow in the subcutaneous adipose tissue which did likewise.

Aged↗
PubMed1988

Measurement of forearm oxygen consumption: role of heating the contralateral hand.

The classical forearm technique widely used for studies of skeletal muscle metabolism requires arterial cannulation. To avoid arterial puncture it is becoming more common to arterialize blood from a contralateral hand vein by local heating. This modification and the classical method have produced contradictory results regarding the contribution of skeletal muscle to glucose-induced thermogenesis. The effect on forearm circulation and the metabolism of heating the contralateral hand was examined before and after an oral glucose load. The results suggest that contralateral heating increases subcutaneous blood flow and decreases skeletal muscle blood flow. This facilitates mixing of superficial blood with deep venous blood. Contralateral heating increased deep venous oxygen saturation and abolished the pronounced glucose-induced increase in oxygen consumption observed in the control experiments after glucose. Heating increased rectal temperature by 0.6 degrees C, and plasma norepinephrine levels were increased compared with the control experiments. The present study explains the conflicting reports on glucose-induced thermogenesis in skeletal muscle and warns against heating the contralateral hand when using the forearm technique.

Adult↗
PubMed1985

Bile acid malabsorption in patients with an ileum reservoir with a long efferent leg to an anal anastomosis.

Biliary metabolism in 11 patients with ileum reservoirs with anal anastomosis and a long efferent leg was studied. Eleven healthy persons served as controls. A significantly higher excretion of bile acids was found in the patients, but they seemed to have a normal cholic acid pool size. The bile acids excreted were cholic acid and chenodeoxycholic acid, the so-called primary bile acids, for more than 90%, whereas the normal controls mainly excreted secondary bile acids (deoxycholic acid and lithocholic acid). Fat excretion was generally not increased in the group but was above normal in two patients. Vitamin B12 absorption was subnormal in two patients and was not correlated to bile acid excretion. Bile acid excretion was not correlated to the weight of feces. The bacterial flora was more feces-like than would have been expected from a normal terminal ileum but was correlated neither to the bile acid excretion nor to the quantity of feces. We conclude that the patients showed dysfunction of the terminal ileum with regard to biliary acid absorption comparable to that found in patients with partial ileal resections.

Adult↗