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Sökning: WFRF:(Ekelund Mats)

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  • Föregående 12[3]4Nästa
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  • Nejdfors, P, et al. (författare)
  • Intestinal permeability in humans is increased after radiation therapy
  • 2000
  • Ingår i: Diseases of the Colon & Rectum. - Springer. - 0012-3706. ; 43:11, s. 1582-1587
  • Tidskriftsartikel (refereegranskat)abstract
    • PURPOSE: Irradiation inflicts acute injuries to the intestinal mucosa with rapid apoptosis induction and subsequent reduction in epithelial surface area. It may therefore be assumed that the intestinal barrier function is affected. The aim of this study was to compare the mucosal permeability in irradiated rectum and nonirradiated sigmoid colon from patients subjected to radiation therapy before surgical treatment for rectal cancer. METHODS: Segments from sigmoid colon and rectum obtained from irradiated and nonirradiated patients were stripped from the serosa-muscle layer and mounted in Ussing diffusion chambers. The mucosa-to-serosa passage of the marker molecules 14C-mannitol, fluorescein isothiocyanate-dextran 4,400, and ovalbumin was followed for 120 minutes. RESULTS: The permeability to the markers was size-dependent and increased linearly across time in all specimens. The passage of all markers was increased in irradiated rectum compared with nonirradiated sigmoid colon, whereas in specimens from nonirradiated patients there were no differences between rectum and sigmoid colon. Histologic signs of crypt and mucosal atrophy were found in the irradiated rectal specimens. CONCLUSIONS: Early gastrointestinal complications after radiation therapy may be the result of mucosal atrophy in addition to mucosal damage, with a loss of barrier integrity.
  • Nejdfors, P, et al. (författare)
  • Mucosal in vitro permeability in the intestinal tract of the pig, the rat, and man: species- and region-related differences
  • 2000
  • Ingår i: Scandinavian Journal of Gastroenterology. - Taylor & Francis. - 1502-7708. ; 35:5, s. 501-507
  • Tidskriftsartikel (refereegranskat)abstract
    • BACKGROUND: The barrier properties of the gastrointestinal mucosa may be studied by measuring its permeability to different-sized marker molecules. Owing to difficulties in obtaining human tissue it is, however, often necessary to extrapolate findings from experimental animals to man. The aim of the present study was to compare regional intestinal mucosal permeability in man, the rat, and the pig, using the same marker molecules and in vitro technique. METHODS: Segments from jejunum, ileum, colon, and rectum were mounted in Ussing diffusion chambers, and the mucosa-to-serosa passage of 14C-mannitol, fluorescein isothiocyanate (FITC)-dextran 4,400, alpha-lactalbumin, ovalbumin, and FITC-dextran 70,000 was studied. RESULTS: Irrespective of species or intestinal region an inverse relationship between the molecular weight of the markers and the permeability was seen. The mannitol permeability was higher in the small intestine than in the colon in man, whereas the rat showed a higher permeability in the ileum than in the jejunum and colon. The FITC-dextran 4,400 permeability was higher in all intestinal regions in the rat than in man and the pig. The macromolecules showed low permeability with no regional differences. CONCLUSIONS: The results showed differences between intestinal regions and between species. Permeability data from the pig correlated fairly well with those of man, whereas the rat differed, making it difficult to extrapolate from the rat to man.
  • Norlén, Per, et al. (författare)
  • The vagus regulates histamine mobilization from rat stomach ECL cells by controlling their sensitivity to gastrin
  • 2005
  • Ingår i: Journal of Physiology. - The Physiological Society. - 1469-7793. ; 564:3, s. 895-905
  • Tidskriftsartikel (refereegranskat)abstract
    • The ECL cells in the oxyntic mucosa secrete histamine in response to gastrin, stimulating parietal cells to produce acid. Do they also operate under nervous control? The present study examines histamine mobilization from rat stomach ECL cells in situ in response to acute vagal excitation and to food or gastrin following vagal or sympathetic denervation. Applying the technique of microdialysis, we monitored the release of histamine by radioimmunoassay. Microdialysis probes were placed in the submucosa on either side of the stomach, 3 days before experiments. The rats were awake during microdialysis except when subjected to electrical vagal stimulation. One-sided electrical vagal stimulation raised serum gastrin and mobilized gastric histamine. However, gastrin receptor blockade prevented the histamine mobilization, indicating that circulating gastrin accounts for the response. Vagal excitation by hypoglycaemia (insulin) or pylorus ligation did not mobilize either gastrin or histamine. The histamine response to food was almost abolished by gastrin receptor blockade, and it was halved on the denervated side after unilateral subdiaphragmatic vagotomy. While the histamine response to a near-maximally effective dose of gastrin was unaffected by vagotomy, the response to low gastrin doses was reduced significantly. Abdominal ganglionic sympathectomy failed to affect the histamine response to either food or gastrin. In conclusion, gastrin is responsible for most of the food-evoked mobilization of ECL-cell histamine. The histamine response to electrical vagal stimulation reflects the effect of circulating gastrin rather than a direct action of the vagus on the ECL cells. Vagal denervation was accompanied by an impaired histamine response to food intake, probably reflecting the right-ward shift of the serum gastrin concentration-histamine response curve. The results suggest that the vagus controls the sensitivity of the ECL cells to gastrin.
  • Pettersson, Jonas, et al. (författare)
  • Muscular exercise can cause highly pathological liver function tests in healthy men.
  • 2008
  • Ingår i: British Journal of Clinical Pharmacology. - John Wiley and Sons Inc.. - 1365-2125. ; 65:2, s. 253-259
  • Tidskriftsartikel (refereegranskat)abstract
    • What is already known about this subject • The occurrence of idiosyncratic drug hepatotoxicity is a major problem in all phases of clinical drug development and the leading cause of postmarketing warnings and withdrawals. • Physical exercise can result in transient elevations of liver function tests. • There is no consensus in the literature on which forms of exercise may cause changes in liver function tests and to what extent. What this study adds • Weightlifting results in profound increases in liver function tests in healthy men used to moderate physical activity, not including weightlifting. • Liver function tests are significantly increased for at least 7 days after weightlifting. • It is important to impose relevant restrictions on heavy muscular exercise prior to and during clinical studies. Aim To investigate the effect of intensive muscular exercise (weightlifting) on clinical chemistry parameters reflecting liver function in healthy men. Methods Fifteen healthy men, used to moderate physical activity not including weightlifting, performed an 1 h long weightlifting programme. Blood was sampled for clinical chemistry parameters [aspartate aminotransferase (AST), alanine aminotransferase (ALT), lactate dehydrogenase (LD), gamma-glutamyl transferase (γGT), alkaline phosphatase (ALP), bilirubin, creatine kinase (CK) and myoglobin] at repeated intervals during 7 days postexercise and at a follow-up examination 10–12 days postexercise. Results Five out of eight studied clinical chemistry parameters (AST, ALT, LD, CK and myoglobin) increased significantly after exercise (P < 0.01) and remained increased for at least 7 days postexercise. Bilirubin, γGT and ALP remained within the normal range. Conclusion The liver function parameters, AST and ALT, were significantly increased for at least 7 days after the exercise. In addition, LD and, in particular, CK and myoglobin showed highly elevated levels. These findings highlight the importance of imposing restrictions on weightlifting prior to and during clinical studies. Intensive muscular exercise, e.g. weightlifting, should also be considered as a cause of asymptomatic elevations of liver function tests in daily clinical practice.
  • Planck, Maria, et al. (författare)
  • Cytogenetic aberrations and heterogeneity of mutations in repeat-containing genes in a colon carcinoma from a patient with hereditary nonpolyposis colorectal cancer.
  • 2002
  • Ingår i: Cancer Genetics and Cytogenetics. - Elsevier. - 0165-4608. ; 134:1, s. 46-54
  • Tidskriftsartikel (refereegranskat)abstract
    • The majority of tumors from patients affected by hereditary nonpolyposis colorectal cancer (HNPCC) exhibit a mutator phenotype characterized by widespread microsatellite instability (MSI) and somatic mutations in repeated sequences in several cancer-associated genes. An inverse relationship between MSI and chromosomal instability (CIN) has been demonstrated and HNPCC-associated tumors are generally characterized by diploid or near-diploid cells with few or no chromosomal rearrangements. We have studied MSI, somatic mutations in repeat-containing genes, DNA-ploidy, and cytogenetic aberrations in a colon carcinoma from a patient with a germline MLH1 mutation. Mutations in coding repeats were assessed in 10 macroscopically separate areas of the primary tumor and in two lymph nodes. Some of the genes studied (E2F4, MSH3, MSH6, TCF4, and TGFBRII) showed a consistent lack of mutations, whereas others (BAX, Caspase-5 and IGFIIR) displayed alterations in some tumor regions but not in others. The tumor had DNA-index 1.1-1.2 and a stable, aberrant karyotype with extra copies of chromosomes 7 and 12 and the structural aberrations i(1q), der(20)t(8;20), and der(22)t(1;22). The finding of CIN, MSI, and somatic mutations in coding repeats in this tumor suggests that these phenomena may act together in HNPCC tumorigenesis. Furthermore, the observed intratumoral heterogeneity of mutations in coding repeats implies these changes occur late in tumorigenesis and, thus, probably play a role in tumor progression rather than initiation.
  • Qader, Saleem, et al. (författare)
  • Expression of islet iNOS and inhibition of glucose stimulated insulin release after long-term lipid infusion in the rat is counteracted by PACAP27.
  • 2007
  • Ingår i: American Journal of Physiology: Endocrinology and Metabolism. - American Physiological Society. - 1522-1555. ; 292:5, s. 1447-1455
  • Tidskriftsartikel (refereegranskat)abstract
    • Chronic exposure of pancreatic islets to elevated plasma lipids ( lipotoxicity) can lead to beta-cell dysfunction, with overtime becoming irreversible. We examined, by confocal microscopy and biochemistry, whether the expression of islet inducible nitric oxide synthase ( iNOS) and the concomitant inhibition of glucose-stimulated insulin release seen after lipid infusion in rats was modulated by the islet neuropeptide pituitary adenylate cyclase-activating polypeptide ( PACAP) 27. Lipid infusion for 8 days induced a strong expression of islet iNOS, which was mainly confined to beta-cells and was still evident after incubating islets at 8.3 mmol/l glucose. This was accompanied by a high iNOS-derived NO generation, a decreased insulin release, and increased cyclic GMP accumulation. No iNOS expression was found in control islets. Addition of PACAP27 to incubated islets from lipid-infused rats resulted in loss of iNOS protein expression, increased cyclic AMP, decreased cyclic GMP, and suppression of the activities of neuronal constitutive ( nc) NOS and iNOS and increased glucose-stimulated insulin response. These effects were reversed by the PKA inhibitor H-89. The suppression of islet iNOS expression induced by PACAP27 was not affected by the proteasome inhibitor MG-132, which by itself induced the loss of iNOS protein, making a direct proteasomal involvement less likely. Our results suggest that PACAP27 through its cyclic AMP- and PKA-stimulating capacity strongly suppresses not only ncNOS but, importantly, also the lipid-induced stimulation of iNOS expression, possibly by a nonproteasomal mechanism. Thus PACAP27 restores the impairment of glucose-stimulated insulin release and additionally might induce cytoprotection against deleterious actions of iNOS-derived NO in beta-cells.
  • Qader, Saleem, et al. (författare)
  • Long-term infusion of nutrients (total parenteral nutrition) suppresses circulating ghrelin in food-deprived rats.
  • 2005
  • Ingår i: Regulatory Peptides. - Elsevier. - 1873-1686. ; 131:Aug 12, s. 82-88
  • Tidskriftsartikel (refereegranskat)abstract
    • Background: Ghrelin derives from endocrine cells (A-like cells) in the stomach (mainly the oxyntic mucosa). Its concentration in the circulation increases during fasting and decreases upon re-feeding. This has fostered the notion that the absence of food in the upper gastrointestinal (GI) tract stimulates the secretion of ghrelin. The purpose of the present study was to determine the concentration of ghrelin in serum and oxyntic mucosa after replacing food with intravenous (iv) infusion of nutrients for 8 days using the technique known as total parenteral nutrition (TPN). Materials and methods: Male Sprague-Dawley rats (200-250 g) were given nutrients (lipids, glucose, amino acids, minerals and vitamins) by iv infusion for 8 days during which time they were deprived of food and water; another group was deprived of food for 24-48 h (fasted controls), while fed controls had free access to food and water. Serum ghrelin, gastrin and pancreastatin concentrations were measured together with the ghrelin content of the oxyntic mucosa. Plasma insulin and glucose as well as serum lipid concentrations were also determined. Results: Fasted rats had higher serum ghrelin than TPN rats and fed controls. The oxyntic mucosal ghrelin concentration (and content) was lower in TPN rats than in fasted rats or fed controls. The serum gastrin and pancreastatin concentrations were lower in TPN rats and fasted rats than in fed controls. The plasma insulin concentration was 87 pmol/l +/- 8 (SEM) in TPN rats compared to 101 16 pmol/l in fed controls; it was 26 14 pmol/l in fasted rats. The basal plasma glucose level was 11 +/- 0.6 mmol/l in TPN rats and 12 +/- 0.8 mmol/l in fed controls; it was 7 +/- 0.3 mmol/l in fasted rats. In TPN rats, the serum concentrations of free fatty acids, triglycerides and cholesterol were increased by 100%, 50% and 25%, respectively, compared to fed controls. Fasted rats had higher circulating concentrations of free fatty acids (20%) and lower concentrations of triglycerides (- 40%) than fed controls; fasted rats did not differ from fed controls with respect to serum cholesterol. Conclusion: The circulating ghrelin concentration is high in situations of nutritional deficiency (starvation) and low in situations of nutritional plenty (free access to food or TPN). The actual presence or absence of food in the GI tract seems irrelevant. Circulating insulin and glucose concentrations did not differ much between TPN rats and fed controls, serum lipids, however, were elevated in the TPN rats. We suggest that elevated blood lipid levels contribute to the suppression of circulating ghrelin in rats subjected to TPN for 8 days.
  • Roth, Bengt, et al. (författare)
  • Biochemical and ultra-structural reactions to parenteral nutrition with two different fat emulsions in rats
  • 1998
  • Ingår i: Intensive Care Medicine. - Springer. - 0342-4642. ; 24:7, s. 716-724
  • Tidskriftsartikel (refereegranskat)abstract
    • OBJECTIVE: To compare the effects on fat metabolism and Kupffer cell morphology by total parenteral nutrition (TPN) with two different fat emulsions. DESIGN: Thirty-two male Sprague-Dawley rats, divided into three groups, were investigated. Rats fed orally were used as a reference group, and a group of rats receiving TPN with fat emulsions containing pure long-chain triglycerides (LCT) was compared to a group of rats receiving fat emulsions containing both long-chain triglycerides and medium-chain triglycerides (MCT/LCT). The TPN regimens were equicaloric and administered continuously via a jugular catheter for 10 days. INTERVENTIONS: After suffocation, blood of the rats was collected for the determination of serum lipids. Epididymal fat and heart were collected for the analysis of lipoprotein lipase (LPL) activities, and liver specimens were saved for analyses of hepatic triglyceride concentration, as well as activities of hepatic lipase (HL) and lysosomal enzymes. Light and electron microscopy were used for examination of the Kupffer cell reaction. RESULTS: Directly after termination of parenteral feeding, the levels of serum triglycerides and high density lipoprotein (HDL) triglycerides were higher in the MCT/LCT group than in the LCT group, while no differences concerning cholesterol and phospholipid concentrations were found. No significant difference in liver steatosis was found between the two TPN groups. Comparison of the TPN groups showed that the MCT/ LCT group had significantly decreased LPL activity in adipose tissue, while the LCT group had significantly increased LPL activity in the heart. The activity of HL was low in both groups, but significantly lower in the LCT group. Lipid accumulation and an increased number of lysosomes were found in all Kupffer cell when TPN with LCTemulsions was used. Moreover, TPN induced a pronounced increase in various liver lysosomal enzyme activities, but there was no notable difference between LCT and MCT/LCT effects. CONCLUSIONS: Compared to treatment with pure LCTemulsions, treatment with MCT/LCT emulsions evoked weaker biochemical reactions in terms of lower activity of lipoprotein lipase in fat and heart together with higher serum and HDL triglyceride levels. Morphological signs of increased Kupffer cell activity such as the appearance of multiple lysosomes and fat vacuoles in the cytoplasm followed treatment with pure LCT emulsions. However, both TPN groups showed a marked increase in activities of liver lysosomal enzymes.
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  • Föregående 12[3]4Nästa
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