Biomedical subjects

J Bülow

Publications and source records attributed to J Bülow.

At least 73 records · Page 4Linked to original sources

PubMed1992

Thermogenic response to epinephrine in the forearm and abdominal subcutaneous adipose tissue.

Whole body energy expenditure, thermogenic and metabolic changes in the forearm, and intercellular glucose concentrations in subcutaneous adipose tissue on the abdomen determined by microdialysis were measured during epinephrine infusion in healthy subjects. After a control period, epinephrine was infused at rates of 0.2 and 0.4 nmol.kg-1 x min-1. Whole body resting energy expenditure was 4.36 +/- 0.56 (SD) kJ/min. Energy expenditure increased to 5.14 +/- 0.74 and 5.46 +/- 0.79 kJ/min, respectively (P < 0.001), during the epinephrine infusions. Respiratory exchange ratio was 0.80 +/- 0.04 in the resting state and did not change. Local forearm oxygen uptake was 3.9 +/- 1.3 mumol.100 g-1 x min-1 in the basal period. During epinephrine infusion, it increased to 5.8 +/- 2.1 (P < 0.03) and 7.5 +/- 2.3 mumol.100 g-1 x min-1 (P < 0.001). Local forearm glucose uptake was 0.160 +/- 0.105 mumol.100 g-1 x min-1 and increased to 0.586 +/- 0.445 and 0.760 +/- 0.534 mumol.100 g-1 x min-1 (P < 0.025). The intercellular glucose concentration in the subcutaneous adipose tissue on the abdomen was equal to the arterial concentration in the basal period but did not increase as much during infusion of epinephrine, indicating glucose uptake in adipose tissue in this condition. If it is assumed that forearm skeletal muscle is representative for the average skeletal muscle, it can be calculated that on average 40% of the enhanced whole body oxygen uptake induced by infusion of epinephrine is taking place in skeletal muscle. It is proposed that adipose tissue may contribute to epinephrine-induced thermogenesis.

Abdomen↗

PubMed1991

Ambulatory measurement of nocturnal fluctuations in subcutaneous blood flow rate in the lower leg of man during 12-h periods with the portable CdTe(Cl) detector. Methodological considerations.

Possible sources of error during long-term measurements of subcutaneous blood flow rate with the portable CdTe(Cl) detector system were ruled out in the present study. Local blood flow rates were recorded in the lower legs of normal human subjects by means of the 133Xe wash-out technique. A good correlation was found between the portable CdTe(Cl) and stationary NaI(Tl) detector systems both prior to (r = 0.88, P less than 0.0001) and after (r = 0.68, P = 0.07) day over night (12 h) measurements. Identical post-ischaemic reactive hyperaemia could be demonstrated by both detector systems 12 h after the application of the isotope depot. This indicates that blood flow rates and vascular reactivity can be measured over 12 h by the portable CdTe(Cl) detector. Identical results were obtained during the 12-h measurements performed with the portable CdTe(Cl) detector attached directly to the skin surface and with the detector elevated above the skin surface. Therefore, geometrical changes were without any influence on our measurements. We conclude that measurements of subcutaneous blood flow rates in the lower leg of human subjects can be performed under out-patients conditions by means of the 133Xe wash-out technique and portable CdTe(Cl) detectors. A skin area greater than or equal to 4 cm should be labelled by means of the atraumatic, epicutaneous labelling technique and the detector attached directly to the skin surface with a single layer of a 20-micron thick gas-tight Mylar membrane interposed between the skin surface and the detector. The investigation of the subcutaneous blood flow rate should not be initiated until at least 90 min after labelling.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1991

Nocturnal variations in subcutaneous blood flow rate in lower leg of normal human subjects.

Subcutaneous adipose tissue blood flow rate was measured in the lower leg of 22 normal human subjects over 12- to 20-h ambulatory conditions. The 133Xe washout technique, portable CdTe(Cl) detectors, and a portable data storage unit were used. The tracer depot was applied on the medial aspect of the right lower leg 10 cm proximal to the malleolar level by means of the epicutaneous, atraumatic labeling technique. The change from upright to supine position from day 1 in the beginning of the night period elicited an instantaneous blood flow rate increment of 30-40% in accordance with a decrease in central and local postural sympathetic vasoconstrictor activity. During sleep, characteristic variations in subcutaneous blood flow were disclosed. The 133Xe washout curve could be divided into three segments with significantly different slopes. Approximately 90 min after the subject went to sleep, an additional blood flow rate increment of considerable magnitude was observed. The mean increase was 84%, but in several cases a greater than 200% increment was measured (maximum 244%). The intra-individual coefficient of variation for the nocturnal blood flow response was in triplicate measurements 25% (n = 9). The hyperemic phase lasted approximately 100 min after which the blood flow rate returned to the level measured at the beginning of the night period. The blood flow rates measured on the second day did not differ from those on the first day. Control measurements performed under similar thermal conditions, but with the subjects kept awake, did not reveal any hyperemic phases. This points toward changes in cardiovascular regulatory mechanisms during sleep.(ABSTRACT TRUNCATED AT 250 WORDS)

Adipose Tissue↗

PubMed1991

Clearance of xenon-133 from bone marrow in patients with small-cell lung cancer.

The aim of this study was to estimate bone-marrow blood flow (BMBF) in man and to correlate this with myelosuppression induced by cytostatic treatment dosed as a function of surface area. Twenty-four patients suffering from small-cell lung cancer participated in the study. Blood flow was measured with the xenon-133 washout technique. The 133Xe clearance measurement took place in conjunction with the pre-treatment bone-marrow staging procedure (ad modern Radner). Tissue samples were taken for microscopy and for the determination of the blood-to-tissue partition coefficient lambda. After the bone-marrow aspiration, 0.1-0.2 ml of 133Xe in saline was injected into the bone marrow and the cannula was removed. Following a hyperaemic phase of 12 min (7-16 min), monoexponential washouts were demonstrated. The median washout rate constant was 0.0063 min-1 (0.0038-0.0098 min-1). Lambda values of 0.3-3.5 ml g were found, but microscopy of the bone marrow showed a fairly large admixture of peripheral blood. Therefore, the lambda values should be taken with caution and absolute blood-flow values were not calculated. The results demonstrated no correlation between 133Xe clearance from crista iliaca and leucocyte or platelet suppression.

Aged↗

PubMed1991

Mucosal/submucosal blood flow in the gut wall determined by local washout of 133Xenon.

A 133Xe washout technique for measuring the blood flow in the intestinal mucosa is introduced and evaluated. In 11 anaesthetized pigs a laparotomy was performed and the mucosal blood flow rate in the intestine of the pig was determined by a local epimucosal application of 133Xe. In both the colon and the small intestine the 133Xe washout plotted in a semilogarithmic diagram showed a multiexponential configuration. Histological examination and localization studies showed shunting by diffusion of 133Xe in the intestinal mucosa explaining the multiexponential configuration of the washout curve. Therefore the initial slope of the washout was used for measuring blood flow rate. Blood flow rate was simultaneously measured by microsphere entrapment technique. There was an excellent correlation between the blood flow rate determined by the two techniques the correlation coefficient R being 0.89 in the small intestine and 0.996 in the colon.

Animals↗

PubMed1990

Vasoactive substances in subchondral bone of the dog knee.

The purpose of the present study was to investigate regulatory mechanisms for subchondral bone blood flow. A model including elevation of joint cavity pressure in the immature dog knee was applied. The role of prostaglandins in bone blood flow regulation was indirectly examined by indomethacin blockade. In six puppies, both venous tamponade of the joint cavity [50% of the mean arterial blood pressure (MAP)] and arterial tamponade (150% of MAP) resulted in a significant increase in the intraosseous pressure of the distal femoral epiphyses (p less than 0.05). During venous tamponade no changes were registered in pO2, pCO2, pH, potassium, and lactate in blood withdrawn from the distal femoral epiphyses. Arterial tamponade resulted in hypoxia, a decrease in pH, and increased lactate. Inhibition of the prostaglandin synthesis did not alter this response pattern. Thus, the present study suggests the presence of a regulatory mechanism for subchondral bone blood flow since venous tamponade did not significantly alter intraosseous gas tensions, pH, lactate, or potassium in spite of elevated venous outlet resistance. The study does not allow any conclusion as to the exact nature of the regulatory mechanism, but local metabolic regulation is likely to be involved as indicated by accumulation of vasoactive substances at higher tamponade levels. Prostaglandins are probably of minor importance in this regulation.

Animals↗

PubMed1990

Urinary bladder blood flow. I. Comparison of clearance of locally injected 99mtechnetium pertechnate and radioactive microsphere technique in dogs.

The blood flow of the dog urinary bladder measured by radioactive microsphere technique was compared to the clearance of locally injected 99mTechnetium pertechnate (99mTc) in the bladder wall. In semilogarithmic plots the 99mTc washout curves showed a multiexponential course. From the initial slopes (median 5.7 min) the bladder blood flow was calculated to be only 30-62% of the results obtained from the radioactive microsphere technique (blood flow in the muscular layer 21.7-44.8 ml/100 g/min). These lower values imply that the rate of removal of the hydrophilic tracer 99mTc at these flow rates is limited by the capillary diffusion capacity. The multiexponential curves reflect recirculation and excretion of 99mTc by the kidneys with accumulation of 99mTc in the bladder. It is concluded, that clearance studies of locally injected 99mTc in the bladder wall are unable to evaluate bladder blood flow.

Animals↗

PubMed1990

Effects of nutrient intake on sympathoadrenal activity and thermogenic mechanisms.

Ingestion of carbohydrate results in a diphasic activation of the sympathoadrenal system. One component is an insulin-mediated activation of the sympathetic nervous system (SNS). This activation is partly a haemodynamic reflex, but it may cause a weak thermogenic effect via beta 1-adrenoceptors in white adipose tissue, the liver and the heart. The second thermogenic component of carbohydrate occurs later when the blood glucose concentration decreases towards baseline levels. This elicits an increased secretion of adrenaline from the adrenal medulla, and the circulating level exceeds the physiological threshold for thermogenic effect. The target is mainly skeletal muscle where thermogenesis is stimulated via beta 2-adrenoceptors. Also the basal metabolic rate and the thermogenic responses to cold and heat exposure, mental stress and exercise, have facultative components. Inhibition of facultative thermogenesis by beta-blockers such as propranolol, diminishes the daily energy expenditure and promotes weight gain and obesity. Although thermogenesis mediated by the sympathoadrenal system accounts for only a small part of the daily energy expenditure, it is sufficient to explain the positive energy balance and weight gain reported in patients receiving treatment with beta-adrenoceptor blocking agents.

Adrenal Glands↗

PubMed1990

Impaired glucose-induced thermogenesis and arterial norepinephrine response persist after weight reduction in obese humans.

A reduced thermic response and an impaired activation of the sympathetic nervous system (SNS) has been reported after oral glucose in human obesity. It is, however, not known whether the reduced SNS activity returns to normal along with weight reduction. The thermic effect of glucose was lower in eight obese patients than in matched control subjects (1.7% vs 9.2%, p less than 0.002). The increase in arterial norepinephrine after glucose was also blunted in the obese patients. After a 30-kg weight loss their glucose and lipid profiles were markedly improved but the thermic effect of glucose was still lower than that of the control subjects (4.2%, p less than 0.001). The glucose-induced arterial norepinephrine response remained diminished in the reduced obese patients whereas the changes in plasma epinephrine were similar in all three groups. The results suggest that a defective SNS may be a cause in the development of obesity.

Adult↗

PubMed1990

Mucosal/submucosal blood flow in the small intestine in pigs determined by local washout of 133Xe and microsphere techniques.

In 11 anaesthetized pigs a laparotomy was performed and the mucosal and submucosal blood flow rate in the small intestine of the pig was determined by a local application of 133Xe and by 6.5-microns radioactive microspheres. The 133Xe washout plotted in a semilogarithmic diagram showed a multiexponential configuration. As localization studies of 133Xe in the intestinal mucosa showed a constant high concentration of 133Xe in the luminal part of the mucosa due to shunting by diffusion, the initial slope of the 133Xe washout was used for blood flow determination in the mucosa/submucosa. There was a good relationship between blood flow determined by the two techniques. The correlation coefficient, R, between the two techniques was 0.89.

Animals↗

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↗

PubMed1990

Reversibility of the effects on local circulation of high lipid concentrations in blood.

Regional perfusion and vascular resistance were examined in different tissues with the radioactive microsphere technique in Göttingen minipigs before, during and after treatment with Intralipid and heparin. This treatment led to an increase in the free fatty acid/albumin molar ratio from 0.39 +/- 0.23 to 3.43 +/- 1.37. Concomitantly a decrease in regional perfusion and an increase in regional vascular resistance was found in skin, adipose tissue, skeletal muscle, kidney, the gastro-intestinal tract, the thyroid and pancreas, while heart and liver showed vasodilatation. The vascular effects were fully reversible when the free fatty acid/albumin molar ratio had normalized. This vascular effect of lipid emulsions has to be considered when patients are treated with parenteral nutrition.

Adipose Tissue↗

PubMed1990

Xenon tissue/blood partition coefficient for pig urinary bladder.

In four landrace pigs the tissue/blood partition coefficient (lambda) for xenon (Xe) for the urinary bladder was calculated after chemical analysis for lipid, water and protein content and determination of the haematocrit. The coefficients varied from bladder to bladder owing to small differences in both the haematocrit and tissue composition. In Xe washout studies of the blood flow of the urinary bladder, we recommend calculating the lambda for Xe from the actual haematocrit and from the median value of tissue composition found in the present study.

Animals↗

PubMed1990

Pancreatic tissue fluid pressure in chronic pancreatitis. Relation to pain, morphology, and function.

The relation between pancreatic tissue fluid pressure and pain, morphology, and function was studied in a cross-sectional investigation. Pressure measurements were performed by percutaneous fine-needle puncture. Thirty-nine patients with chronic pancreatitis were included, 25 with pain and 14 without pain. The pressure was higher in patients with pain than in patients without pain (p = 0.000001), and this was significantly related to a pain score from a visual analogue scale (p less than 0.001). Patients with pancreatic pseudocysts had both higher pressure and higher pain score than patients without (p = 0.004 and p = 0.0003, respectively). The pressure was significantly related (inversely) to pancreatic duct diameter only in the group of 19 patients with earlier pancreatic surgery (R = -0.57, p = 0.02). The pressure was not related to functional factors or the presence of pancreatic calcifications. In conclusion, pancreatic tissue fluid pressure is a valuable indicator of pain in chronic pancreatitis.

Abdominal Pain↗

PubMed1990

Evaluation of pancreatic tissue fluid pressure measurements intraoperatively and by sonographically guided fine-needle puncture.

The aim of the present study was to evaluate the needle method for pancreatic tissue fluid pressure measurements. Clinical evaluation was performed in 24 patients with chronic pancreatitis, comparing repeated pressure measurements via sonographically guided fine-needle puncture and intraoperative pressure measurements by direct puncture of pancreatic tissue and duct. In patients with chronic pancreatitis we found small week-to-week variations in sonographically guided percutaneous pressure measurements and good agreement between preoperative percutaneous pressure measurements and intraoperative pressure measurements via direct puncture. Furthermore, no significant difference was seen between pancreatic duct and tissue fluid pressure. The technical evaluation was performed by repeated pressure measurements in human pancreatic autopsy specimens and living rats in a pressure chamber at various external pressure levels. The basic calibration of the method evaluated by means of this pressure chamber study showed sufficient precision and accuracy of the needle technique for clinical and investigative purposes. In conclusion, our results suggest that pancreatic tissue fluid pressure can be reliably assessed by the needle technique.

Animals↗

PubMed1990

Evaluation of pancreatic tissue fluid pressure and pain in chronic pancreatitis. A longitudinal study.

Pancreatic tissue fluid pressure and pain were compared in a longitudinal study in nine patients undergoing drainage operations for pain in chronic pancreatitis. Pressure measurements were performed percutaneously before the operation, intraoperatively before and after the drainage procedure, and percutaneously at follow-up study 1 year after the operation. The pressures were compared with 2-week pain scores. The median predrainage pressures were increased (27 mm Hg; range, 19-34 mm Hg; normal, 7 mm Hg; range, 2-13 mm Hg). The drainage operations led to a 45% pressure decrease (range, 0-77%). At 1-year follow-up study the pressure was increased in the patients with recurrent pain, and there was a significant relation between pressure and pain (R = 0.85, p less than 0.02). Furthermore, patients with an intraoperative pressure decrease greater than 10 mm Hg had a pain-free postoperative period. The duration of the pain-free period was significantly related to the size of the intraoperative pressure decrease (R = 0.79, p less than 0.03). These results further suggest that there is a causal relationship between pancreatic tissue fluid pressure and pain in chronic pancreatitis and that the success of the drainage procedure may be predicted by intraoperative pancreatic tissue fluid pressure measurements.

Adult↗

PubMed1989

Femoral artery recanalisation with percutaneous angioplasty and segmentally enclosed plasminogen activator.

To establish whether re-occlusion of the femoral artery could be prevented, in 6 consecutive patients undergoing percutaneous transluminal angioplasty (PTA) for superficial femoral artery occlusion the recanalised segment was isolated, with a 7-French double-balloon catheter. 5 mg recombined human tissue-type plasminogen activator (rt-PA) and 1000 IU heparin were then infused into the enclosed space for 30 minutes, followed by intravenous heparin for 24 hours. At 10 and 30 days all 6 patients had evidence of recanalisation and remission of symptoms. Mean ankle-arm pressure index improved by 72% at 24 hours, by 118% at 10 days, and by 103% at 30 days after the procedure. No patients had major complications. Treatment of superficial femoral artery occlusions by PTA with rt-PA and intravenous heparin seems to prevent rethrombosis.

Aged↗

PubMed1989

Changes of high-energy phosphorous compounds in skeletal muscle during glucose-induced thermogenesis in man. A 31P MR spectroscopy study.

By the use of invasive techniques, skeletal muscle has been shown to contribute to thermogenesis induced by glucose in humans. In an attempt to study this phenomenon by a non-invasive method, this study investigated intracellular high-energy phosphorous compounds in calf muscle by 31P MR spectroscopy during an oral glucose load in healthy lean subjects. The inorganic phosphate concentration increased gradually (P less than 0.05) after glucose intake. The phosphocreatine/inorganic phosphate rate decreased (P less than 0.05) and the estimated ADP concentration increased. ATP and intracellular pH remained unchanged after the glucose administration. No changes were seen in the control experiments. The processes responsible for the decreased energy state of the skeletal muscle cell may be an obligatory conversion of glucose to glycogen. Also, facultative processes, such as sodium/potassium pumping and substrate cycles stimulated by the sympatho-adrenal system, may be partly responsible.

Adenosine Diphosphate↗