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Biomedical subjects

J F Pedersen

Publications and source records attributed to J F Pedersen.

At least 19 recordsLinked to original sources
PubMed2006

Duplex ultrasound of the superior mesenteric artery in chronic pancreatitis.

Blood flow in the superior mesenteric artery (SMA) increases after a meal due to a vasoactive effect of the decomposed food. In exocrine pancreatic insufficiency, the digestion of food is compromised. We used duplex ultrasound to test the hypothesis that blood flow in the SMA after a meal increases less in patients with pancreatic insufficiency than in control persons. We studied 16 patients with chronic pancreatitis, eight of them with exocrine insufficiency, and eight healthy volunteers. The resistive index (RI) in the SMA was determined before and after a liquid meal. The RI reflects the downstream circulatory resistance, giving a precise description of mesenteric hyperaemia. Both groups of patients with chronic pancreatitis unexpectedly had lower fasting RI than controls, 0.818 and 0.815 vs 0.851, p = 0.028 and p = 0.0030, respectively. Postprandialy there was significantly less decrease in RI (less increase in flow) in patients with exocrine insufficiency than in controls, 0.055 vs 0.099, p = 0.0047. There was a significant trend for a less pronounced postprandial decrease in RI with more impaired pancreatic function (p = 0.0036). Our study thus demonstrates a reduced postprandial increase in SMA flow in patients with exocrine pancreatic insufficiency, and suggests an increased fasting SMA flow in chronic pancreatitis. Further studies are needed to evaluate the possible role of the test-meal-induced shift in RI in the SMA and of a lower-than-normal fasting RI in the diagnosis and monitoring of chronic pancreatitis.

Adolescent↗
PubMed2006

Serotonin and superior mesenteric artery resistance index.

OBJECTIVE: Serotonin is a vasoactive neuroendocrine substance and serotonergic drugs are promising agents for the treatment of functional gastrointestinal disorders. The effect of serotonin on superior mesenteric blood flow in humans is unknown. The aim of this study was to examine the effect of exogenous serotonin on superior mesenteric artery blood flow, as estimated by the resistance index with Doppler ultrasound, in healthy human volunteers. MATERIAL AND METHODS: Six fasting healthy adult volunteers of both genders were studied. Transabdominal Doppler ultrasound was used to evaluate the effects of either a standard meal or intravenous infusion of serotonin (2.5-20 nmol kg-1 min-1) on the superior mesenteric artery resistance index, platelet-depleted plasma levels of serotonin, blood pressure, heart rate and electrocardiogram. RESULTS: All subjects had the same patterns of response to meal and serotonin stimulation. Meal stimulation decreased the mean resistance index from 0.84+/-0.04 to 0.72+/-0.02 (p = 0.0004) and increased platelet-depleted-plasma levels of serotonin from 50+/-36 to 61+/-46 nmol L-1 (p = 0.04). Serotonin stimulation increased the mean resistance index from 0.82+/-0.04 to 0.88+/-0.03 (p = 0.006) and mean platelet-depleted-plasma levels of serotonin from 44+/-24 to 83+/-37 nmol L-1 (p = 0.03). Most subjects reported minor short-lived adverse effects. Electrocardiogram results were unchanged during all examinations. CONCLUSIONS: We conclude that intravenous infusion of serotonin increases the resistance index of the superior mesenteric artery (increases downstream resistance) in healthy adult volunteers.

Adult↗
PubMed2005

Sonographic comparison of gastric emptying of broth and water: is there a promoting cephalic factor?

PURPOSE: To examine the emptying times of broth and water, and explore the possibility of a cephalic influence on gastric emptying. MATERIAL AND METHODS: On different days each of twelve healthy volunteers had meals of either 350 ml water or 350 ml broth. Subsequently ten volunteers had meals of water alone and of water followed by sham feeding with broth. The antral area was determined at sonography five times before the meal as a baseline, and every 1-4 minutes after the meal. The time until the antral area had decreased to 150% of baseline (T150) was determined and used as surrogate expression of gastric emptying time. RESULTS: The mean T150 was for water 20.3 min (range 12-40), and was for broth significantly shorter 12.6 min (5-21), P = 0.0020. In the subsequent series the mean T150 was 28.5 min (18-49) for water, and significantly shorter for water followed by sham feeding, 22.8 (14-40), P = 0.0078. CONCLUSION: Broth empties faster from the stomach than plain water, probably because of a "cephalic phase" stimulation of gastric motility via the vagus nerve.

Adult↗
PubMed2005

Hepatic transit time of ultrasound contrast in biopsy characterized liver disease.

PURPOSE: To study the hepatic transit time of an ultrasound contrast agent in patients with liver disease, and to evaluate the mechanism(s) of the well-established shorter cubital vein to hepatic vein transit time in cirrhosis. MATERIAL AND METHODS: Thirty-four patients scheduled for Menghini liver biopsy were studied by ultrasound after injection of 2.5 g Levovist (Schering, Berlin, Germany) into an arm vein. The time from injection until the first appearance of contrast echoes in the hepatic artery and hepatic veins was registered. Hepatic transit time was the difference between the two. RESULTS: Biopsy showed cirrhosis in 9 patients, other diffuse hepatic pathology in 23 patients, and normal liver in 2 patients. Mean hepatic vein arrival time was earlier in cirrhosis than in other liver disease (19.4 s versus 26.0 s; P = 0.013), and hepatic transit time was shorter (6.6 s versus 11.6 s; P = 0.024). A hepatic transit time <10 s was found in all patients with cirrhosis, but also in 10 of 23 patients with other liver pathology. CONCLUSION: Hepatic transit time measurement could not be used to distinguish between cirrhosis and other hepatic pathology, but a transit time = 10 s excluded cirrhosis. The earlier hepatic vein arrival time in cirrhosis is apparently mainly caused by intrahepatic shunting rather than by early arrival of contrast to the liver.

Biopsy↗
PubMed2005

Abnormal hepatic vein Doppler waveform in patients without liver disease.

In patients with liver cirrhosis Doppler ultrasound often detects absence of the retrograde (hepatopetal) flow phase in the hepatic vein, suggestive of an increased stiffness of the liver parenchyma around the vein. This is rarely or never reported in healthy control persons. We examined the frequency of absent retrograde flow in a consecutive series of 139 patients referred for abdominal ultrasound. We used state-of-the-art ultrasound scanners, and placed the Doppler gate so that in non-forced end-expiration it would sample the right hepatic vein 4-6 cm from the vena cava. There was no association between the hepatic vein flow pattern and age, sex or body mass index. 43 of 139 studied patients showed absent retrograde flow. Review of the case records revealed liver disease in 26 patients and no sign of liver disease in 17 patients. We suggest that absent retrograde flow in the hepatic veins may be seen not only in patients with overt liver disease but also in apparently liver-healthy patients.

Adult↗
PubMed2004

Glucagon-like peptide-2 inhibits antral emptying in man, but is not as potent as glucagon-like peptide-1.

BACKGROUND: GLP-1 (glucagon-like peptide-1) and GLP-2 (glucagon-like peptide-2) are released in equimolar amounts in response to meal ingestion. GLP-1 inhibits gastric emptying and reduces postprandial gastric and exocrine pancreatic secretion and may play a physiological regulatory role in controlling appetite and energy intake in humans. The role of GLP-2 is more uncertain. Based on the results of animal studies, it has been suggested that GLP-2 may induce intestinal epithelial growth and inhibit gastric motility. The aim of this study was to determine to what extent GLP-2 alone or together with GLP-1 inhibits gastric emptying and the sensation of hunger in man. METHODS: Eight healthy volunteers were tested in a double-blind, placebo-controlled fashion. Antral emptying of a liquid meal and hunger ratings were determined using ultrasound technology and visual analogue scales scoring during infusions of saline, GLP-2 (0.5, and 1.0 pmol kg body wt(-1) min(-1)), GLP-1 (0.5 pmol kg body wt(-1) min(-1)) or GLP-1 and GLP-2 (0.5 pmol kg body wt(-1) min(-1)). RESULTS: The GLP-2 infusions resulted in a dose-dependent increase in antral emptying time (35%; ns and 75%; P = 0.049) compared to saline, but GLP-2 was less potent than GLP-1, which increased the antral emptying time by 192% (P < 0.001). Addition of GLP-2 to the GLP-1 infusion did not alter the antral emptying time compared with GLP-1 alone. The GLP-1 infusion decreased the sensation of hunger compared with saline (P = 0.023), whereas the two GLP-2 infusions had no significant effect. Addition of GLP-2 to the GLP-1 infusion did not decrease the sensation of hunger further. CONCLUSIONS: Both GLP-1 and GLP-2 inhibit antral emptying in man, but GLP-1 is more potent.

Adult↗
PubMed2004

Comparison of brown midrib-6 and -18 forage sorghum with conventional sorghum and corn silage in diets of lactating dairy cows.

Total mixed rations containing conventional forage sorghum, brown midrib (bmr)-6 forage sorghum, bmr-18 forage sorghum, or corn silage were fed to Holstein dairy cows to determine the effect on lactation, ruminal fermentation, and total tract nutrient digestion. Sixteen multiparous cows (4 ruminally fistulated; 124 d in milk) were assigned to 1 of 4 diets in a replicated Latin square design with 4-wk periods (21-d adaptation and 7 d of collection). Diets consisted of 40% test silage, 10% alfalfa silage, and 50% concentrate mix (dry basis). Acid detergent lignin concentration was reduced by 21 and 13%, respectively, for the bmr-6 and bmr-18 sorghum silages when compared with the conventional sorghum. Dry matter intake was not affected by diet. Production of 4% fat-corrected milk was greatest for cows fed bmr-6 (33.7 kg/d) and corn silage (33.3 kg/d), was least for cows fed the conventional sorghum (29.1 kg/d), and was intermediate for cows fed the bmr-18 sorghum (31.2 kg/d), which did not differ from any other diet. Total tract neutral detergent fiber (NDF) digestibility was greatest for the bmr-6 sorghum (54.4%) and corn silage (54.1%) diets and was lower for the conventional (40.8%) and bmr-18 sorghum (47.9%) diets. In situ extent of NDF digestion was greatest for the bmr-6 sorghum (76.4%) and corn silage (79.0%) diets, least for the conventional sorghum diet (70.4%), and intermediate for the bmr-18 sorghum silage diet (73.1%), which was not different from the other diets. Results of this study indicate that the bmr-6 sorghum hybrid outperformed the conventional sorghum hybrid; the bmr-18 sorghum was intermediate between conventional and bmr-6 in most cases. Additionally, the bmr-6 hybrid resulted in lactational performance equivalent to the corn hybrid used in this study. There are important compositional differences among bmr forage sorghum hybrids that need to be characterized to predict animal response accurately.

Animal Nutritional Physiological Phenomena↗
PubMed2003

Tender points are not sites of ongoing inflammation -in vivo evidence in patients with chronic tension-type headache.

Increased muscle tenderness is the most prominent finding in patients with tension-type headache, and it has recently been shown that muscle blood flow is diminished in response to static exercise in tender points in these patients. Although tenderness has been ascribed to local inflammation and release of inflammatory mediators, the interstitial concentration of inflammatory mediators has not previously been studied in tender muscles of patients with tension-type headache. The aim of the present study was to investigate in vivo concentrations of prostaglandin E2 (PGE2), adenosine 5'-triphosphate (ATP), glutamate, bradykinin and other metabolites in a tender point of patients with chronic tension-type headache, in the resting state as well as in response to static exercise, and to compare findings with measurements in a matched non-tender point of healthy controls. We recruited 16 patients with chronic tension-type headache and 17 healthy control subjects. Two microdialysis catheters were inserted into the trapezius muscle and dialysates were collected at rest, 15 and 30 min after start of static exercise (10% of maximal force) and 15 and 30 min after end of exercise. All samples were coded and analysed blindly. There was no difference in resting concentration of any inflammatory mediators or metabolites between tender patients and non-tender controls (P > 0.05). We also found no difference in change in interstitial concentration of ATP, PGE2, glutamate, glucose, pyruvate and urea from baseline to exercise and post-exercise periods between patients and controls (P > 0.05). The present study provides in vivo evidence of normal interstitial levels of inflammatory mediators and metabolites in tender trapezius muscle in patients with chronic tension-type headache during both rest and static exercise. Thus, our data suggest that tender points in these patients are not sites of ongoing inflammation.

Adult↗
PubMed2003

A modified sonographic technique for assessment of gastric emptying of liquid.

PURPOSE: Ultrasound scanning is replacing scintigraphy in studies of gastric emptying of liquid, but both have considerable day-to-day variability. This study describes a modified ultrasound technique for assessing gastric emptying of liquid, and evaluates the inter- and intraindividual variation in emptying time. MATERIAL AND METHODS: On different days, each of 12 healthy volunteers had meals of 350 ml broth. The antral area was measured at sonography 5 times before the meal as a baseline, and every 1-4 min after the meal. The time until the antral area had decreased to 150% of baseline (T150) was determined and used as surrogate expression of gastric emptying time. RESULTS: The mean T150 for a broth meal was 12.6 min (range 5-21) and 13.5 min (6-23) (first and second meal, respectively). The standard deviation of the differences between the 12 pairs of repeated measurements was 3.1 min and the coefficient of variation was 24%. CONCLUSION: Ultrasound monitoring of antral size after a liquid meal is a well suited method for assessing gastric emptying of liquid.

Adult↗
PubMed2002

The use of video glasses at ultrasound-guided interventions.

PURPOSE: Video glasses form a virtual image in front of the user. We investigated the utility of video glasses at US-guided interventions. MATERIAL AND METHODS: The video glasses were tested at 75 consecutive US-guided interventions. The operator sees the US image in front of him, and below the glasses, simply by moving his eyes, he can see the patient and the field of intervention. RESULTS: The video glasses could be used at all 75 US-guided interventions. The image quality was below that of the US monitor, but adequate. The working posture was improved, it was easy to get accustomed to using the system, there was no increased time consumption, and the patients felt comfortable with the set-up. CONCLUSION: Use of video glasses facilitates US-guided interventions.

Equipment Design↗
PubMed2002

In vivo evidence of altered skeletal muscle blood flow in chronic tension-type headache.

Painful impulses from tender pericranial muscles may play a major role in the pathophysiology of chronic tension-type headache. Firm evidence for peripheral muscle pathology as a cause of muscle pain and chronic headache is still lacking. Using a microdialysis technique, we aimed to estimate in vivo blood flow and interstitial lactate concentrations in the trapezius muscle at rest and during static exercise in patients with chronic tension-type headache and in healthy subjects. We recruited 16 patients with chronic tension-type headache and 17 healthy control subjects. Two microdialysis catheters were inserted into the trapezius muscle (on the non-dominant side) of subjects, and dialysates were collected at rest, 15 and 30 min after the start of static exercise (10% of maximal force) and 15 and 30 min after the exercise was completed. All samples were coded and analysed blind. The primary endpoints were to detect a difference between patients and controls in changes of muscle blood flow and the interstitial lactate concentration from baseline to exercise and post-exercise periods. The increase in muscle blood flow from baseline to exercise and post-exercise periods was significantly lower in patients than controls (P = 0.03). There was no difference in resting blood flow between patients and controls (P = 0.43). Resting interstitial concentration of lactate did not differ between patients (2.51 +/- 0.18 mM; mean +/- standard error of the mean) and controls (2.35 +/- 0.23 mM, P = 0.57). There was no difference in change in interstitial lactate from baseline to exercise and post-exercise periods between patients and controls (P = 0.38). The present study provides in vivo evidence of decreased blood flow in response to static exercise in a tender muscle in patients with chronic tension-type headache. We suggest that, because of increased excitability of neurones in the CNS, the central interpretation and response to normal sensory input are altered in patients with chronic tension-type headache. This may lead to enhanced sympathetically mediated vasoconstriction and thereby a decreased blood flow in response to static exercise.

Adolescent↗
PubMed2001

Hepatic vein transit time of an ultrasound contrast agent: simplified procedure using pulse inversion imaging.

The aim of this study was to ascertain whether a new ultrasound technique, namely pulse inversion imaging, could assess the arrival of a contrast agent in the hepatic veins, and to describe possible advantages of this procedure in determining transit time over a previously described method based upon spectral Doppler quantification. 15 subjects were scanned using pulse inversion imaging. A bolus injection of 2.5 g Levovist (Schering AG, Berlin, Germany) 300 mg x ml(-1) was given into an antecubital vein. Median transit times of 16 s (range 14-20 s) were found in patients with liver cirrhosis (n=4), 22 s (range 16-27 s) in patients with focal liver lesions (n=8) and 31 s (range 30-32 s) in control subjects (n=3). The maximum interobserver variation was 2 s and the maximum intraobserver variation was 3 s (n=10). Transit time was assessed by both pulse inversion imaging and spectral Doppler quantification in six patients. Comparison of the two methods showed transit times within 2 s apart in five patients and within 5 s apart in one patient. In conclusion, it is possible to assess transit time using pulse inversion imaging. This method is simpler than a previously described method requiring computer analysis. Moreover, several liver veins can be assessed simultaneously. Different transit times were observed in different liver veins in two patients with liver tumours. A short transit time (<27 s) appears to be found only in patients with liver disease. After transit time assessment, it is possible to use the injected contrast agent for late phase imaging of the liver parenchyma.

Adult↗
PubMed1999

[Gallstones and pancreatic necrosis in acute pancreatitis].

The purpose of this study was to investigate the occurrence of gallstones and the severity of acute pancreatitis in a Danish population, and in severe cases, the relation between pancreatic necrosis and gallstones. We used Ranson's prognostic scoring system to measure the severity of acute pancreatitis, ultrasonography for detecting biliary stones, and computed tomography or laparotomy for detecting pancreatic necrosis. During a two year period, we registered 101 patients. Approximately 70% were mild cases, and we found 18 patients with and 53 patients without gallstones. Among patients with severe cases, we observed 14 with and 16 without gallstones. There was a significantly higher proportion of gallstones in severe cases. Eight of 30 patients with severe pancreatitis had pancreatic necrosis, but we found no relation between the occurrence of necrosis and gallstones. We conclude that patients with gallstone related pancreatitis have more severe disease than patients without stones, but the complication of pancreatic necrosis is not related to gallstones.

Acute Disease↗
PubMed1999

Fat and mesenteric blood flow.

BACKGROUND: The introduction of fat to the duodenum leads to an increase in mesenteric blood flow. The exact mechanism, however, is unknown. In this study we investigate the influence of the terminal carboxy group of the oleic acid molecule on superior mesenteric artery blood flow. METHODS: In six healthy male volunteers duplex ultrasound was used to evaluate the effects of duodenal perfusion of 48 mmol oleic acid and 48 mmol oleyl alcohol on superior mesenteric artery blood flow variables and diameter. RESULTS: The blood flow variables time-average velocity and maximal diastolic velocity increased significantly, and the resistance index decreased significantly during perfusion with oleic acid, but during oleyl alcohol perfusion no changes were found. No significant changes in vessel diameter were observed at any time. CONCLUSION: The carboxy group of the oleic acid molecule has an important role in the duodenum in mediating the postprandial increase in superior mesenteric artery blood flow.

Adult↗
PubMed1999

Renal duplication artefacts in ultrasound imaging.

A duplication artefact is sometimes encountered on ultrasound examination of the left kidney. It is caused by sound beam refraction between the spleen and adjacent fat. The purpose of this study was to analyse the frequency and types of such artefacts, and examine their physical background. The examiner searched for a left renal duplication artefact in 150 unselected abdominal ultrasound studies. A disturbed contour of the left kidney could be formed in 34 of 123 patients in whom the spleen was in the image without covering the kidney completely. An artefact was seen significantly more often when the lower pole of the spleen was rounded (30/87) than when it was wedge shaped (4/36) (p < 0.02). The artefacts could be categorized into complete upper pole duplication (n = 4), incomplete upper pole duplication (n = 14) and bayonet artefact (n = 16). The thickness of the renal cortex appeared reduced with upper pole duplication artefacts owing to a geometric image compression, which could also be seen in an in vitro experiment. Left renal duplication artefacts are not rare when the upper part of the kidney is examined by ultrasound through the spleen.

Adolescent↗