40 results on '"Sigthorsson G"'
Search Results
2. Pituitary Insufficiency in the Acute Phase of Traumatic Brain Injury or Subarachnoid Hemorrhage: A Prospective Study.
- Author
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Sigurjonsson, P, primary, Jonasdottir, D, additional, Olafsson, IH, additional, Karason, S, additional, Karlsdottir, G, additional, Sigthorsson, G, additional, Benediktsson, R, additional, and Sigurjonsdottir, H, additional
- Published
- 2010
- Full Text
- View/download PDF
3. Effects of NSAIDs on cryoprobe-induced gastric ulcer healing in rats
- Author
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Tibble, J., Sigthorsson, G., Caldwell, C., Palmer, R. H., and Bjarnason, I.
- Published
- 2001
4. Faecal calprotectin and faecal occult blood tests in the diagnosis of colorectal carcinoma and adenoma
- Author
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Tibble, J, Sigthorsson, G, Foster, R, Sherwood, R, Fagerhol, M, and Bjarnason, I
- Published
- 2001
5. Selective inhibition of COX-2 in humans is associated with less gastrointestinal injury: a comparison of nimesulide and naproxen
- Author
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Shah, A A, Thjodleifsson, B, Murray, F E, Kay, E, Barry, M, Sigthorsson, G, Gudjonsson, H, Oddsson, E, Price, A B, Fitzgerald, D J, and Bjarnason, I
- Published
- 2001
6. COX-2 inhibition with rofecoxib does not increase intestinal permeability in healthy subjects: a double blind crossover study comparing rofecoxib with placebo and indomethacin
- Author
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Sigthorsson, G, Crane, R, Simon, T, Hoover, M, Quan, H, Bolognese, J, and Bjarnason, I
- Published
- 2000
7. A simple method for assessing intestinal inflammation in Crohnʼs disease
- Author
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Tibble, J, Teahon, K, Thjodleifsson, B, Roseth, A, Sigthorsson, G, Bridger, S, Foster, R, Sherwood, R, Fagerhol, M, and Bjarnason, I
- Published
- 2000
8. Gastric acid secretion in cyclooxygenase-1 deficient mice
- Author
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Borrelli, F., Welsh, N. J., Sigthorsson, G., Simpson, R., Palizban, A., Bjarnason, I., and Tavares, I. A.
- Published
- 2000
9. Uncoupling of intestinal mitochondrial oxidative phosphorylation and inhibition of cyclooxygenase are required for the development of NSAID-enteropathy in the rat
- Author
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SOMASUNDARAM, S, SIGTHORSSON, G, SIMPSON, R J, WATTS, J, JACOB, M, TAVARES, I A, RAFI, S, ROSETH, A, FOSTER, R, PRICE, A B, WRIGGLESWORTH, J M, and BJARNASON, I
- Published
- 2000
10. High prevalence of NSAID enteropathy as shown by a simple faecal test
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Tibble, J A, Sigthorsson, G, Foster, R, Scott, D, Fagerhol, M K, Roseth, A, and Bjarnason, I
- Published
- 1999
11. Enantiomers of flurbiprofen can distinguish key pathophysiological steps of NSAID enteropathy in the rat
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Mahmud, T, Somasundaram, S, Sigthorsson, G, Simpson, R J, Rafi, S, Foster, R, Tavares, I A, Roseth, A, Hutt, A J, Jacob, M, Pacy, J, Scott, D L, Wrigglesworth, J M, and Bjarnason, I
- Published
- 1998
12. Intestinal permeability and inflammation in patients on NSAIDs
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Sigthorsson, G, Tibble, J, Hayllar, J, Menzies, I, Macpherson, A, Moots, R, Scott, D, Gumpel, M J, and Bjarnason, I
- Published
- 1998
13. Mitochondrial damage: a possible mechanism of the "topical" phase of NSAID induced injury to the rat intestine
- Author
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Somasundaram, S, Rafi, S, Hayllar, J, Sigthorsson, G, Jacob, M, Price, A B, Macpherson, A, Mahmod, T, Scott, D, Wrigglesworth, J M, and Bjarnason, I
- Published
- 1997
14. Intestinal tolerability of nitroxybutyl-flurbiprofen in rats
- Author
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Somasundaram, S, Rafi, S, Jacob, M, Sigthorsson, G, Mahmud, T, Sherwood, R, Price, A B, Macpherson, A, Scott, D, Wrigglesworth, J M, and Bjarnason, I
- Published
- 1997
15. Book Reviews
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Jaakkola Maarit, Sigthorsson Gauti, and Andresen Kenneth
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Communication. Mass media ,P87-96 - Published
- 2022
- Full Text
- View/download PDF
16. Effect of Pentavac and measles-mumps-rubella (MMR) vaccination on the intestine. (Inflammation and Inflammatory Bowel Disease)
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Thjodleifsson, B., Davidsdottir, K., Agnarsson, U., Sigthorsson, G., Kjeld, M., and Bjarnason, I.
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Measles-mumps-rubella vaccine -- Physiological aspects ,Enterocolitis -- Risk factors ,Autism -- Risk factors ,Health - Abstract
Background: The safety of infant vaccination has been questioned in recent years. In particular it has been suggested that the measles, mumps, and rubella (MMR) vaccination leads to brain damage [...]
- Published
- 2002
17. P81 Pituitary insufficiency in the acute phase of traumatic brain injury or subarachnoid hemorrhage: a prospective study
- Author
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Sigurjonsson, P., primary, Jonasdottir, A.D., additional, Olafsson, I.H., additional, Karason, S., additional, Karlsdottir, G., additional, Sigthorsson, G., additional, Benediktsson, R., additional, and Sigurjonsdottir, H.A., additional
- Published
- 2010
- Full Text
- View/download PDF
18. Comparison of the effects of naproxen and the COX-2 selective NSAID, nimesulide, on prostanoid formation in man
- Author
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Murray, FE, primary, Shah, AA, additional, Thjodleifsson, B, additional, Oddsson, E, additional, Gudjonsson, H, additional, Sigthorsson, G, additional, Crane, R, additional, Bjarnason, I, additional, and Fitzgerland, DJ, additional
- Published
- 1998
- Full Text
- View/download PDF
19. Faecal calprotectin: A simple method for the diagnosis of NSAID-induced enteropathy
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Tibble, JA, primary, Foster, R, additional, Sigthorsson, G, additional, Scott, D, additional, Roseth, A, additional, and Bjarnason, I, additional
- Published
- 1998
- Full Text
- View/download PDF
20. Gastric acid secretion in cyclooxygenase-l deficient mice.
- Author
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Borrelli, F., Welsh, N. J., Sigthorsson, G., Simpson, R., Palizban, A., Bjarnason, I., and Tavares, I. A.
- Abstract
Background: Constitutive cyclooxygenase‐1 enzyme synthesizes prostaglandins which are thought to play an important role in the functional integrity of the stomach gastric mucosa. Recently, it was shown that cyclooxygenase‐1 deficient mutant mice did not develop spontaneous gastric pathology and appear less sensitive to indomethacin‐induced gastric damage. Aim: To investigate gastric acid secretion in cyclooxygenase‐1 deficient mutant mice. Methods: The basal and histamine or isobutyl methylxanthine‐stimulated acid secretion in stomachs of cyclooxygenase‐1 deficient homozygous mice and the effect of indomethacin was compared with that of heterozygous and wild‐type mice using isolated lumen perfused mouse stomachs, in organ baths, monitored by pH‐electrodes. Results: There was no significant difference in the basal or histamine stimulated gastric acid secretion between wild‐type or heterozygous or homozygous mice. However, isobutyl methylxanthine was more potent in the cyclooxygenase‐1 deficient and heterozygous mice than in wild‐type mice. Indomethacin, at concentrations below 1 mM, had no effect on either basal or histamine stimulated acid secretion in any of the mice populations. Conclusion: Gastric acid secretion is maintained without prostaglandin involvement in cyclooxygenase‐1 deficient mice. The finding that basal and histamine‐stimulated gastric acid secretion was similar in the cyclooxygenase‐1 deficient, compared to wild‐type mice is consistent with the lack of spontaneous gastric pathology in the cyclooxygenase‐1 deficient mice. [ABSTRACT FROM AUTHOR]
- Published
- 2000
- Full Text
- View/download PDF
21. Comparison of the Intestinal Toxicity of Celecoxib, a Selective COX-2 Inhibitor, and Indomethacin in the Experimental Rat.
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Tibble, J. A., Sigthorsson, G., Foster, R., and Bjarnason, I.
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CELECOXIB , *INDOMETHACIN - Abstract
Background: It is suggested that the gastrointestinal toxicity of conventional non-steroid anti-inflammatory drugs (NSAIDs) is due to a 'topical' effect in addition to inhibition of the mucosal constitutive cyclo-oxygenase-1 (COX-1) enzyme. COX-2 selective inhibitors have been shown to have excellent gastrointestinal tolerability, but it is not known whether this is due to their selectivity and/or a lack of a 'topical' effect. We assessed the effects of celecoxib (a highly selective COX-2 inhibitor) on key pathophysiologic events in NSAID enteropathy. Methods: The 'topical' effects of indomethacin and celecoxib were assessed in vitro (coupled mitochondrial respiration) and in vivo (mitochondrial electron microscopy) and the consequences by study of intestinal permeability (51-Cr-labelled ethylenediaminetetraacetic acid urinary excretion) and inflammation. We also assessed intestinal prostanoid levels (prostaglandin E, PGE) and the propensity of the drugs to induce intestinal ulcers. Results: Indomethacin uncoupled mitochondrial oxidative phosphorylation in vitro and in vivo, caused a significant (P < 0.0001) increase in intestinal permeability, caused mucosal inflammation and a 90% decline in intestinal PGE levels, and was associated with multiple small intestinal ulcers. Celecoxib caused no significant increase in any of these parameters, did not decrease intestinal PGE levels, and caused no intestinal ulcers. Conclusions: The intestinal tolerability of celecoxib appears to be due to a combination of the absence of a `topical' damaging effect and selective COX inhibition. [ABSTRACT FROM AUTHOR]
- Published
- 2000
- Full Text
- View/download PDF
22. The Prevalence and Severity of Intestinal Disaccharidase Deficiency in Human Immunodeficiency Virus-Infected Subjects.
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Taylor, C., Hodgson, K., Sharpstone, D., Sigthorsson, G., Coutts, M., Sherwood, R., Menzies, I., Gazzard, B., and Bjarnason, I.
- Subjects
GASTROINTESTINAL diseases ,HIV-positive persons ,SYMPTOMS - Abstract
Background: Gastrointestinal symptoms are distressing features of human immunodeficiency virus (HIV) infection, and management is often empirical, including withdrawal of dietary lactose. We assessed the prevalence and severity of intestinal disaccharidase deficiency in vitro and in vivo. Methods: Fifty-four HIV-seropositive patients (19 HIV well ± mild diarrhoea, 7 acquired immunodeficiency syndrome (AIDS) well, and 28 AIDS with diarrhoea) were studied with a combined non-invasive absorption-permeability-disaccharidase test that enables quantitative assessment of the rate of intestinal hydrolysis of lactose, sucrose, and palatinose. Thirty patients had jejunal biopsy specimens suitable for histomorphometric assessment, and 36 had in vitro disaccharidase activity measurement. Results: Patients with HIV (with mild diarrhoea) and AIDS (with and without severe diarrhoea) had frequent but mild histomorphometric changes in jejunal specimens. This was associated with frequent (21%-100%) and often severe in vitro jejunal disaccharidase deficiency. In vivo hydrolysis of lactose, sucrose, and palatinose was impaired in 25%-75% of patients, apart from HIV well patients, who were normal. The prevalence of the in vivo lactase and sucrase deficiency was significantly (P < 0.006) lower than in vitro and severe in about 30%. Conclusions: Intestinal disaccharidase deficiency is common both in vitro and in vivo in HIV-seropositive patients but sufficiently severe to consider lactose withdrawal only in about a quarter of the patients with AIDS and diarrhoea. [ABSTRACT FROM AUTHOR]
- Published
- 2000
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23. Comparison of Indomethacin and Nimesulide, a Selective Cyclooxygenase-2 Inhibitor, on Key Pathophysiologic Steps in the Pathogenesis of Nonsteroidal Anti-Inflammatory Drug Enteropathy in the Rat.
- Author
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SIGTHORSSON, G., JACOB, M., WRIGGLESWORTH, J., SOMASUNDARAM, S., TAVARES, I., FOSTER, R., ROSETH, A., RAFI, S., MAHMUD, T., SIMPSON, R., and BJARNASON, I.
- Subjects
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INTESTINAL diseases , *NONSTEROIDAL anti-inflammatory agents , *CYCLOOXYGENASES - Abstract
Background: The predicted gastrointestinal tolerability of specific cyclooxygenase-2 inhibitors could be due to either a lack of 'topical' irritation and/or lack of effect on cyclooxygenase-1. Methods: Key pathophysiologic steps (in vitro and in vivo uncoupling, intestinal prostanoid levels (prostaglandin E, thromboxane B[sub 2], and 6-keto-prostaglandin F[sub 1α]), intestinal permeability ([sup 51]Cr-ethylenediaminetetraacetic acid), inflammation (faecal excretion of a granulocyte marker protein), and ulcer counts) in enteropathy induced by nonsteroidal anti-inflammatory drugs were assessed after administration of indomethacin, 10 mg/kg, and 15 (roughly equipotent), 30, and 60 mg/kg of the preferential cyclooxygenase-2 inhibitor nimesulide. Results: Indomethacin uncoupled oxidative phosphorylation at lower concentrations than nimesulide in vitro. Indomethacin was associated with electron microscopy changes suggestive of uncoupling in 60%-70% of enterocytes examined, whereas nimesulide affected 10%-30% of enterocytes, depending on the dose. Indomethacin increased intestinal permeability and caused inflammation and ulcers with 71%-96% reductions in prostanoid levels. Nimesulide at 15 mg/kg caused no damage, whereas 30 and 60 mg/kg nimesulide were associated with significant decreases in mucosal prostanoids (46%-75%), but only the 60-mg/kg dose caused a transient increase in intestinal permeability. However, at none of the doses did nimesulide cause intestinal inflammation or ulcers. Conclusions: These results endorse the idea that selective cyclooxygenase-2 inhibitors may be associated with some gastrointestinal tolerance due to their selectivity for cyclooxygenase-2, inhibiting cyclooxygenase-1 at only very high doses, and reduced topical irritation. [ABSTRACT FROM AUTHOR]
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- 1998
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24. Subclinical intestinal inflammation and sacroiliac changes in relatives of patients with ankylosing spondylitis
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Bjarnason, I., Helgason, K.O., Geirsson, A.J., Sigthorsson, G., Reynisdottir, I., Gudbjartsson, D., Einarsdottir, A.S., Sherwood, R., Kristjansson, K., Kjartansson, O., and Thjodleifsson, B.
- Abstract
Background & Aims: It has been suggested that subclinical intestinal inflammation plays a pathogenic role in the spondylarthropathy of ankylosing spondylitis (AS). We assessed the possible presence and inheritance pattern of subclinical intestinal inflammation in first-degree relatives of patients with AS. The relationship between this inflammation and the subjects' HLA-B27 genotype as well as computerized tomographic sacroiliac abnormalities was also assessed. Methods: A total of 124 of 213 (58%) available first-degree relatives of 47 patients with AS in Iceland underwent investigation for intestinal inflammation (fecal calprotectin concentration), HLA-B27 genotyping, and computerized tomography of the sacroiliac joints. Results: A total of 41% of the first-degree relatives had subclinical intestinal inflammation, whereas 15 of 17 spouses were normal. Variance components analyses suggest that the inheritance pattern of this inflammation is affected by a major additive gene. Some sacroiliac changes, suggestive of early AS, differed significantly between subjects with and without subclinical intestinal inflammation (mean diameter of subchondral cysts [2.9 vs. 1.2 mm; P = 0.026] and blurring of joint margins [9 of 44 (20%) vs. 1 of 41 (2%); P = 0.02]). Intestinal inflammation and sacroiliac changes did not relate to the subjects' HLA-B27 status. Conclusions: Many first-degree relatives of patients with AS appear to have an inherited abnormality that leads to subclinical intestinal inflammation. The association between the presence of this inflammation and the sacroiliac changes suggests that it may play a pathogenic role in the spondylarthropathy of AS.
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- 2003
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25. A simple method for assessing intestinal inflammation in Crohn's disease
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Fagerhol, M., Tibble, J., Sigthorsson, G., Bridger, S., Foster, R., Sherwood, R., Bjarnason, I., Teahon, K., Thjodleifsson, B., and Roseth, A.
- Abstract
Background and aimsAssessing the presence and degree of intestinal inflammation objectively, simply, and reliably is a significant problem in gastroenterology. We assessed faecal excretion of calprotectin, a stable neutrophil specific marker, as an index of intestinal inflammation and its potential use as a screening test to discriminate between patients with Crohn's disease and those with irritable bowel syndrome.MethodsThe validity of faecal calprotectin as a marker of intestinal inflammation was assessed in 22 patients with Crohn's disease (35 studies) by comparing faecal excretions and concentrations using four day faecal excretion of 111indium white cells. A cross sectional study assessed the sensitivity of faecal calprotectin concentration for the detection of established Crohn's disease (n=116). A prospective study assessed the value of faecal calprotectin in discriminating between patients with Crohn's disease and irritable bowel syndrome in 220 patients referred to a gastroenterology clinic.ResultsFour day faecal excretion of 111indium (median 8.7%; 95% confidence interval (CI) 7-17%; normal <1.0%) correlated significantly (p<0.0001) with daily (median ranged from 39 to 47 mg; normal <3 mg; r=0.76-0.82) and four day faecal calprotectin excretion (median 101 mg; 95% CI 45-168 mg; normal <11 mg; r=0.80) and single stool calprotectin concentrations (median 118 mg/l; 95% CI 36-175 mg/l; normal <10 mg/l; r=0.70) in patients with Crohn's disease. The cross sectional study showed a sensitivity of 96% for calprotectin in discriminating between normal subjects (2 mg/l; 95% CI 2-3 mg/l) and those with Crohn's disease (91 mg/l; 95% CI 59-105 mg/l). With a cut off point of 30 mg/l faecal calprotectin has 100% sensitivity and 97% specificity in discriminating between active Crohn's disease and irritable bowel syndrome.ConclusionThe calprotectin method may be a useful adjuvant for discriminating between patients with Crohn's disease and irritable bowel syndrome.
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- 2000
26. Intestinal permeability and inflammation in Crohn's disease and their first degree relatives
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Thjodleifsson, B., Sigthorsson, G., Gunnarsdottir, A., Norland, H., Oddsson, E., Gudjonsson, H., Einarsson, S., Meddings, J., Roseth, A., Fagerhol, M.K., Crane, R., Kjeld, M., and Bjarnason, I.
- Published
- 1998
- Full Text
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27. Status on fasting definition for blood sampling in the Nordic countries - time for a harmonized definition.
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Grankvist K, Sigthorsson G, Kristensen GB, Pelanti J, and Nybo M
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- Scandinavian and Nordic Countries, Time Factors, Blood Chemical Analysis standards, Fasting, Practice Guidelines as Topic
- Abstract
The preanalytical phase contains a vast number of practices whose variation may influence the results of laboratory testing and should, therefore, be standardized. The Working Group on Preanalytical Phase of the European Federation of Clinical Chemistry and Laboratory Medicine (EFLM WG-PA) has suggested a standardization of venous blood specimen collection (VBSC) requirements for fasting samples including 12 h fasting time and water ad lib in the morning prior to specimen collection. The Nordic Scientific Preanalytical Working Group investigated the fasting definitions used in the Nordic countries. The Internet was assessed for stated fasting definitions of official organizations, larger laboratories, or laboratory groups. Fasting instructions for VBSC generally demanded patients to abstain from alcohol a day prior to, and to abstain from coffee, tea, smoking, and snuff intake in the morning of VBSC. Norway had a national fasting definition. Required fasting times varied from 8 to 14 h. The amount of water allowed in the morning of VBSC varied from ad lib to half a glass of water. The list of analytes, where fasting was required, held 9-15 analytes except for Finland with 65 analytes. Implementation of the EFLM WG-PRE standardization of VBSC requirements for fasting samples would decrease preanalytical variability and be beneficial for medical decisions and patient data comparison. We suggest the laboratories in the Nordic countries to implement the suggested fasting requirements, which are in line with those used when fasting reference intervals were established in the Nordic reference interval project.
- Published
- 2018
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28. Hypopituitarism 3 and 12 months after traumatic brain injury and subarachnoid haemorrhage.
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Jonasdottir AD, Sigurjonsson P, Olafsson IH, Karason S, Sigthorsson G, and Sigurjonsdottir HA
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- Adolescent, Adult, Aged, Brain Injuries, Traumatic blood, Disease Progression, Female, Follow-Up Studies, Glasgow Coma Scale, Hormones blood, Humans, Male, Middle Aged, Prevalence, Retrospective Studies, Subarachnoid Hemorrhage blood, Time Factors, Young Adult, Brain Injuries, Traumatic epidemiology, Hypopituitarism epidemiology, Subarachnoid Hemorrhage epidemiology
- Abstract
Objective: High prevalence of hypopituitarism (HP) has been reported after traumatic brain injury (TBI) and subarachnoid haemorrhage (SAH). The aim of the study was to prospectively evaluate the prevalence and progression of HP in patients after TBI and SAH in Icelandic population., Design: A 12 month prospective single-centre study., Methods and Procedures: A total of 27 patients were included, 15 patients with TBI and 12 patients with SAH. Pituitary function was evaluated with baseline hormone measurements and diagnostic tests. An insulin tolerance test was used unless contraindicated, then the GHRH-arginine test and Synachten test were used., Results: At three months, 16.7% (2/12) of the patients had HP after TBI and 33.3% (4/12) after SAH. At 12 months, 21.4% (3/14) of patients had HP after TBI and 9.1% (1/11) after SAH. Gonadotropin deficiency was the most common deficiency at 3 months and GH and gonadotropin deficiency at 12 months., Conclusions: There is a considerable risk of HP after TBI and reason to study pituitary function further in patients with SAH. We believe that neuroendocrine evaluation is important in these patients. Since recovery commonly occurs 12 months after the event, evaluation should be performed after that time if not clinically indicated earlier.
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- 2018
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29. Discovery of 4-[(2S)-2-{[4-(4-chlorophenoxy)phenoxy]methyl}-1-pyrrolidinyl]butanoic acid (DG-051) as a novel leukotriene A4 hydrolase inhibitor of leukotriene B4 biosynthesis.
- Author
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Sandanayaka V, Mamat B, Mishra RK, Winger J, Krohn M, Zhou LM, Keyvan M, Enache L, Sullins D, Onua E, Zhang J, Halldorsdottir G, Sigthorsdottir H, Thorlaksdottir A, Sigthorsson G, Thorsteinnsdottir M, Davies DR, Stewart LJ, Zembower DE, Andresson T, Kiselyov AS, Singh J, and Gurney ME
- Subjects
- Biological Availability, Butyrates chemistry, Butyrates therapeutic use, Crystallography, X-Ray, Enzyme Inhibitors chemistry, Enzyme Inhibitors therapeutic use, Epoxide Hydrolases biosynthesis, Heterocyclic Compounds chemistry, Heterocyclic Compounds therapeutic use, Humans, Ligands, Myocardial Infarction drug therapy, Peptide Fragments chemistry, Solubility, Stroke drug therapy, Structure-Activity Relationship, Butyrates pharmacology, Cardiovascular Diseases drug therapy, Drug Discovery methods, Epoxide Hydrolases antagonists & inhibitors, Heterocyclic Compounds pharmacology
- Abstract
Both in-house human genetic and literature data have converged on the identification of leukotriene 4 hydrolase (LTA(4)H) as a key target for the treatment of cardiovascular disease. We combined fragment-based crystallography screening with an iterative medicinal chemistry effort to optimize inhibitors of LTA(4)H. Ligand efficiency was followed throughout our structure-activity studies. As applied within the context of LTA(4)H inhibitor design, the chemistry team was able to design a potent compound 20 (DG-051) (K(d) = 26 nM) with high aqueous solubility (>30 mg/mL) and high oral bioavailability (>80% across species) that is currently undergoing clinical evaluation for the treatment of myocardial infarction and stroke. The structural biology-chemistry interaction described in this paper provides a sound alternative to conventional screening techniques. This is the first example of a gene-to-clinic paradigm enabled by a fragment-based drug discovery effort.
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- 2010
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30. Structure-activity relationship studies leading to the identification of (2E)-3-[l-[(2,4-dichlorophenyl)methyl]-5-fluoro-3-methyl-lH-indol-7-yl]-N-[(4,5-dichloro-2-thienyl)sulfonyl]-2-propenamide (DG-041), a potent and selective prostanoid EP3 receptor antagonist, as a novel antiplatelet agent that does not prolong bleeding.
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Singh J, Zeller W, Zhou N, Hategan G, Mishra RK, Polozov A, Yu P, Onua E, Zhang J, Ramírez JL, Sigthorsson G, Thorsteinnsdottir M, Kiselyov AS, Zembower DE, Andrésson T, and Gurney ME
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- Acrylamides chemical synthesis, Acrylamides chemistry, Blood Coagulation drug effects, Drug Discovery, Humans, Ligands, Molecular Structure, Platelet Aggregation Inhibitors chemical synthesis, Platelet Aggregation Inhibitors chemistry, Receptors, Prostaglandin E, EP3 Subtype, Stereoisomerism, Structure-Activity Relationship, Sulfones chemical synthesis, Sulfones chemistry, Acrylamides pharmacology, Hemorrhage, Platelet Aggregation drug effects, Platelet Aggregation Inhibitors pharmacology, Receptors, Prostaglandin E antagonists & inhibitors, Sulfones pharmacology
- Abstract
The EP(3) receptor on the platelet mediates prostaglandin E(2) potentiation of thrombogenic coagonists including collagen and adenosine diphosphate (ADP). A pharmacophore driven approach led to the identification of diverse peri-substituted heterocycles as potent and selective EP(3) receptor antagonists. A simultaneous chemical optimization and druglike assessment of prioritized molecules converged on a lead compound 50 (DG-041) that displayed favorable in vitro and functional activities as an inhibitor of human platelet aggregation. This agent is currently in human clinical trials for the treatment of atherothrombosis.
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- 2010
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31. Antagonists of the EP3 receptor for prostaglandin E2 are novel antiplatelet agents that do not prolong bleeding.
- Author
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Singh J, Zeller W, Zhou N, Hategen G, Mishra R, Polozov A, Yu P, Onua E, Zhang J, Zembower D, Kiselyov A, Ramírez JL, Sigthorsson G, Bjornsson JM, Thorsteinsdottir M, Andrésson T, Bjarnadottir M, Magnusson O, Fabre JE, Stefansson K, and Gurney ME
- Subjects
- Animals, Clopidogrel, Dinoprostone antagonists & inhibitors, Dinoprostone metabolism, Female, Hemorrhage prevention & control, Humans, Male, Platelet Aggregation Inhibitors chemistry, Purinergic P2 Receptor Antagonists, Rats, Receptors, Prostaglandin E, EP3 Subtype, Receptors, Purinergic P2Y12, Thrombosis drug therapy, Thrombosis metabolism, Ticlopidine analogs & derivatives, Ticlopidine pharmacology, Acrylamides pharmacology, Platelet Aggregation drug effects, Platelet Aggregation Inhibitors pharmacology, Prostaglandin Antagonists pharmacology, Receptors, Prostaglandin E antagonists & inhibitors, Sulfones pharmacology
- Abstract
Myocardial infarction and stroke are caused by blood clots forming over a ruptured or denuded atherosclerotic plaque (atherothrombosis). Production of prostaglandin E(2) (PGE(2)) by an inflamed plaque exacerbates atherothrombosis and may limit the effectiveness of current therapeutics. Platelets express multiple G-protein coupled receptors, including receptors for ADP and PGE(2). ADP can mobilize Ca(2+) and through the P(2)Y(12) receptor can inhibit cAMP production, causing platelet activation and aggregation. Clopidogrel (Plavix), a selective P(2)Y(12) antagonist, prevents platelets from clotting but thereby increases the risk of severe or fatal bleeding. The platelet EP(3) receptor for PGE(2), like the P(2)Y(12) receptor, also inhibits cAMP synthesis. However, unlike ADP, facilitation of platelet aggregation via the PGE(2)/EP(3) pathway is dependent on co-agonists that can mobilize Ca(2+). We used a ligand-based design strategy to develop peri-substituted bicylic acylsulfonamides as potent and selective EP(3) antagonists. We show that DG-041, a selective EP(3) antagonist, inhibits PGE(2) facilitation of platelet aggregation in vitro and ex vivo. PGE(2) can resensitize platelets to agonist even when the P(2)Y(12) receptor has been blocked by clopidogrel, and this can be inhibited by DG-041. Unlike clopidogrel, DG-041 does not affect bleeding time in rats, nor is bleeding time further increased when DG-041 is co-administered with clopidogrel. This indicates that EP(3) antagonists potentially have a superior safety profile compared to P(2)Y(12) antagonists and represent a novel class of antiplatelet agents.
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- 2009
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32. Role of bile in pathogenesis of indomethacin-induced enteropathy.
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Jacob M, Foster R, Sigthorsson G, Simpson R, and Bjarnason I
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- Animals, Bile metabolism, Bile Ducts metabolism, Bile Ducts surgery, Feces chemistry, Intestinal Absorption drug effects, Intestine, Small metabolism, Intestine, Small pathology, Leukocyte L1 Antigen Complex metabolism, Male, Permeability, Rats, Rats, Sprague-Dawley, Ulcer metabolism, Ulcer pathology, Anti-Inflammatory Agents, Non-Steroidal toxicity, Bile Acids and Salts pharmacology, Indomethacin toxicity, Intestine, Small drug effects, Ulcer chemically induced
- Abstract
Ingestion of non-steroidal anti-inflammatory drugs (NSAIDs) causes an enteropathy. The pathogenesis involves biochemical initiation of intestinal mucosal damage due to NSAID-induced inhibition of cyclooxygenase and the topical effects of these drugs. These effects lead to increased intestinal permeability and inflammation. Luminal bile acids play a controversial role in the damage produced by these drugs. The aim of this study was to determine the role of bile in producing the enteropathy caused by indomethacin, an NSAID commonly used in toxicity studies. Sprague-Dawley rats were subjected to bile duct ligation. Twenty-four hours later, they were dosed with indomethacin. Intestinal permeability ((51)Cr-EDTA) and inflammation (faecal calprotectin) were measured in the animals at various time periods after the dose. Intestinal permeability was significantly higher in rats 1-6 h after dosing with indomethacin, but not at 24-29 h or day 4, when compared with corresponding values for control animals. Excretion of faecal calprotectin was elevated in the indomethacin-treated rats. The drug-treated animals showed no evidence of ulceration when they were sacrificed 29 h or a week after the dose of indomethacin. Bile acids per se did not affect intestinal permeability or faecal excretion of calprotectin, when given along with indomethacin or its vehicle. We conclude that macroscopic small bowel damage does not occur with indomethacin if bile is excluded, despite the induction of permeability and inflammation. This study highlights the importance of luminal factors, such as bile, in producing indomethacin-induced ulceration in the rat small intestine.
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- 2007
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33. Subclinical intestinal inflammation: an inherited abnormality in Crohn's disease relatives?
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Thjodleifsson B, Sigthorsson G, Cariglia N, Reynisdottir I, Gudbjartsson DF, Kristjansson K, Meddings JB, Gudnason V, Wandall JH, Andersen LP, Sherwood R, Kjeld M, Oddsson E, Gudjonsson H, and Bjarnason I
- Subjects
- Adult, Aged, Crohn Disease epidemiology, Feces chemistry, Female, Humans, Leukocyte L1 Antigen Complex analysis, Male, Middle Aged, Prevalence, Crohn Disease genetics
- Abstract
Background & Aims: One approach to unraveling the genetics of complex inherited disease, such as Crohn's disease, is to search for subclinical disease markers among unaffected family members. We assessed the possible presence, prevalence, and inheritance pattern of subclinical intestinal inflammation in apparently healthy relatives of patients with Crohn's disease., Methods: A total of 49 patients with Crohn's disease, 16 spouses, and 151 (58%) of 260 available first-degree relatives underwent a test for intestinal inflammation (fecal calprotectin concentration). The mode of inheritance was assessed from 36 index patients (by variance component analysis) when more than 50% of relatives were studied., Results: Fecal calprotectin concentrations in patients with Crohn's disease (47 mg/L; confidence interval [CI], 27-95 mg/L) and relatives (11 mg/L; CI, 9-14 mg/L) differed significantly (P < 0.0001) from controls (4 mg/L; CI, 3-5 mg/L), whereas that of the spouses did not (4 mg/L; CI, 3-6 mg/L; P > 0.5). Fecal calprotectin concentration was increased in 49% of all relatives studied. The increased fecal calprotectin concentration among the relatives of the 36 index patients had an inheritance pattern that was most consistent with an additive inheritance pattern., Conclusions: There is a high prevalence of subclinical intestinal inflammation in first-degree relatives of patients with Crohn's disease that conforms best to an additive inheritance pattern. The genetic basis for this abnormality may represent a risk factor for Crohn's disease.
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- 2003
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34. Use of surrogate markers of inflammation and Rome criteria to distinguish organic from nonorganic intestinal disease.
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Tibble JA, Sigthorsson G, Foster R, Forgacs I, and Bjarnason I
- Subjects
- Adolescent, Adult, Aged, Aged, 80 and over, Anti-Inflammatory Agents, Non-Steroidal adverse effects, Biomarkers, Diagnosis, Differential, Endoscopy, Gastrointestinal, Female, Humans, Leukocyte L1 Antigen Complex, Male, Middle Aged, Permeability, Prospective Studies, Sensitivity and Specificity, Colonic Diseases, Functional diagnosis, Feces chemistry, Intestinal Diseases diagnosis, Membrane Glycoproteins analysis, Neural Cell Adhesion Molecules analysis
- Abstract
Background & Aims: Differentiating symptoms of irritable bowel syndrome (IBS) from those of organic intestinal disease is a familiar problem for physicians. The aim of this study was to assess the sensitivity, specificity, and odds ratios (ORs) of fecal calprotectin, small intestinal permeability, Rome I criteria, and laboratory markers of inflammation (erythrocyte sedimentation rate [ESR], C-reactive protein [CRP], blood count) in distinguishing organic from nonorganic intestinal disease., Methods: A total of 602 new referrals to a gastroenterology clinic who had symptoms suggestive of IBS or organic intestinal disease were studied for these parameters. All patients underwent invasive imaging (barium/endoscopic examination) and other investigations as appropriate, with physicians blinded to the results of fecal calprotectin and intestinal permeability., Results: A total of 263 patients were diagnosed with organic disease and 339 with IBS. At 10 mg/L, the sensitivity and specificity of calprotectin for organic disease were 89% and 79%, respectively, and that of intestinal permeability for small intestinal disease were 63% and 87%, respectively. Sensitivity of positive Rome criteria for IBS was 85% with a specificity of 71%. An abnormal calprotectin test had an OR for disease of 27.8 (95% confidence interval [CI], 17.6-43.7; P < 0.0001) compared with ORs of 4.2 (95% CI, 2.9-6.1; P < 0.0001) and 3.2 (95% CI, 2.2-4.6; P < 0.0001) for elevated CRP and ESR values. An abnormal permeability test gave an OR of 8.9 (95% CI, 5.8-14.0; P < 0.0001) for small intestinal disease. The OR for IBS with positive Rome criteria was 13.3 (95% CI, 8.9-20.0)., Conclusions: Fecal calprotectin, intestinal permeability, and positive Rome I criteria provide a safe and noninvasive means of helping differentiate between patients with organic and nonorganic intestinal disease.
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- 2002
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35. COX-1 and 2, intestinal integrity, and pathogenesis of nonsteroidal anti-inflammatory drug enteropathy in mice.
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Sigthorsson G, Simpson RJ, Walley M, Anthony A, Foster R, Hotz-Behoftsitz C, Palizban A, Pombo J, Watts J, Morham SG, and Bjarnason I
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- Animals, Cyclooxygenase 1, Cyclooxygenase 2, Cyclooxygenase 2 Inhibitors, Cyclooxygenase Inhibitors pharmacology, Dinoprostone metabolism, Enteritis chemically induced, Enteritis pathology, Female, Intestinal Diseases metabolism, Isoenzymes genetics, Male, Membrane Proteins, Mice, Mice, Inbred C57BL, Mice, Knockout genetics, Permeability drug effects, Prostaglandin-Endoperoxide Synthases genetics, Pyrazoles pharmacology, Ulcer chemically induced, Anti-Inflammatory Agents, Non-Steroidal pharmacology, Indomethacin pharmacology, Intestinal Diseases chemically induced, Intestines physiology, Isoenzymes physiology, Prostaglandin-Endoperoxide Synthases physiology
- Abstract
Background & Aims: The pathogenesis of nonsteroidal anti-inflammatory drug-induced enteropathy is controversial, but it is thought that cyclooxygenase-1 (COX-1) inhibition is of pivotal importance. We compared small intestinal function and morphology in untreated wild-type, COX-1- and COX-2-deficient mice and the effect of indomethacin, selective COX-1 (SC-560), and COX-2 (celecoxib) inhibition., Methods: Intestinal permeability ((51)CrEDTA), inflammation (fecal granulocyte marker protein), prostaglandin E(2) (PGE(2)) levels, and macroscopic and microscopic appearances were assessed at baseline and after the drugs., Results: COX-1(-/-) animals were normal except for a 97% decrease in intestinal PGE(2) levels. COX-1(+/+) and COX-1(-/-) animals reacted in a similar way to indomethacin. However, celecoxib, having caused no damage in COX-1(+/+) animals, caused small bowel ulcers in COX-1(-/-) animals. Selective inhibition of COX-1 decreased intestinal PGE(2) levels in COX-2(+/+) and COX-2(-/-) animals by 95%-97%, but caused only small bowel ulcers in the latter group. Dual inhibition of COX-1 and COX-2 in wild-type animals resulted in similar small bowel damage. Between 40% and 50% of untreated COX-2(-/-) animals had increased intestinal permeability and inflammation. Some had ileal ulcers that were distinctively different from indomethacin-induced ulcers. Furthermore, long-term celecoxib administration in wild-type animals was associated with similar damage as in the COX-2(-/-) mice., Conclusions: COX-1 deficiency or inhibition and short-term COX-2 inhibition are compatible with normal small intestinal integrity. Dual inhibition of the COX enzymes leads to damage similar to that seen with indomethacin. Long-term COX-2 deficiency or inhibition is associated with significant intestinal pathology despite normal intestinal PGE(2) levels, suggesting a role for COX-2 in the maintenance of small intestinal integrity in the mouse.
- Published
- 2002
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36. Epidemiology and differential diagnosis of NSAID-induced injury to the mucosa of the small intestine.
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Smale S, Tibble J, Sigthorsson G, and Bjarnason I
- Subjects
- Algorithms, Diagnosis, Differential, Humans, Inflammatory Bowel Diseases chemically induced, Inflammatory Bowel Diseases etiology, Spondylarthropathies complications, United Kingdom epidemiology, Anti-Inflammatory Agents, Non-Steroidal adverse effects, Inflammatory Bowel Diseases diagnosis, Inflammatory Bowel Diseases epidemiology, Intestinal Mucosa drug effects, Intestine, Small drug effects
- Abstract
Non-steroidal anti-inflammatory drugs cause small-bowel inflammation in about 60% of patients receiving these drugs long-term. The inflammation is associated with small intestinal bleeding, protein loss, ulcers and occasionally strictures. Treatment options for NSAID enteropathy include metronidazole, sulphasalazine and misoprostol, and some patients may require surgery. The diagnosis of NSAID enteropathy is not always straightforward. It is especially difficult to differentiate it from the ileitis associated with spondylarthropathy and, at times, that of Crohn's disease. An investigational algorithm is suggested for this purpose. In the last decade a number of small-bowel diseases have been identified, where none were thought to exist, because of the increasing use of enteroscopy and new sensitive tests for intestinal inflammation. Optimal treatments of these conditions are still to be studied., (Copyright 2001 Harcourt Publishers Ltd.)
- Published
- 2001
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37. Surrogate markers of intestinal inflammation are predictive of relapse in patients with inflammatory bowel disease.
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Tibble JA, Sigthorsson G, Bridger S, Fagerhol MK, and Bjarnason I
- Subjects
- Adolescent, Adult, Aged, Biomarkers, Feces chemistry, Female, Humans, Intestinal Mucosa metabolism, Leukocyte L1 Antigen Complex, Male, Membrane Glycoproteins analysis, Middle Aged, Neural Cell Adhesion Molecules analysis, Permeability, Prognosis, Recurrence, Sensitivity and Specificity, Colitis, Ulcerative metabolism, Crohn Disease metabolism, Enteritis metabolism
- Abstract
Background & Aims: Prediction of relapse of inflammatory bowel disease has important implications for therapeutic strategies. We assessed whether measurement of intestinal permeability and inflammation could predict relapse of inflammatory bowel disease (IBD)., Methods: Forty-three patients with Crohn's disease (CD) and 37 with ulcerative colitis (UC) in clinical remission provided a stool sample to be assayed for calprotectin (a neutrophil-specific marker), and patients with CD additionally underwent a small intestinal permeability test. Relapse was defined using clinical disease activity indices., Results: Twenty-five (58%) patients with CD and 19 (51%) with UC had a relapse over the 12-month period. Median calprotectin levels in the relapse groups (122 mg/L for CD, 123 mg/L for UC; normal <10 mg/L) differed significantly (P<0.0001) from those of the nonrelapse groups (41.5 mg/L for CD, 29.0 mg/L for UC). At 50 mg/L, the sensitivity and specificity of calprotectin for predicting relapse in all patients with IBD were 90% and 83%, respectively. Permeability in the CD patients who relapsed (median, 0.075; normal <0.04) differed significantly (P = 0. 004) from that in the nonrelapse group (median, 0.038). At the level of 0.05, the sensitivity and specificity of permeability in predicting relapse were 84% and 61%, respectively., Conclusions: Fecal calprotectin predicts clinical relapse of disease activity in patients with CD and UC, whereas small intestinal permeability is a useful predictor of relapse in patients with small intestinal CD.
- Published
- 2000
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38. Assessment of ileal pouch inflammation by single-stool calprotectin assay.
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Thomas P, Rihani H, Røseth A, Sigthorsson G, Price A, Nicholls RJ, and Bjarnason I
- Subjects
- Biomarkers analysis, Biopsy, Colonoscopy, Diagnosis, Differential, Enzyme-Linked Immunosorbent Assay, Female, Humans, Leukocyte L1 Antigen Complex, Macrophages pathology, Male, Neutrophils pathology, Pouchitis metabolism, T-Lymphocytes pathology, Calcium-Binding Proteins analysis, Feces chemistry, Membrane Glycoproteins analysis, Neural Cell Adhesion Molecules analysis, Pouchitis diagnosis
- Abstract
Purpose: Assessment of inflammation within the ileal pouch to establish a diagnosis of "pouchitis" requires both pouch endoscopy and biopsy because there can be a poor correlation between macroscopic and histologic assessments of inflammation. A simplified diagnostic test would be of clinical advantage. Calprotectin is a stable myelomonocytic protein, measurable in feces. It quantitatively relates to inflammation within the gastrointestinal tract. This study was designed to compare single and 24-hour stool measurements of calprotectin in patients with and without evidence of ileal pouch inflammation with endoscopic, histologic, and immunohistochemical indices., Methods: Twenty-four-hour stool collections were made in ileal pouch patients, 9 with and 15 without (7 with ulcerative colitis and 8 with familial polyposis coli) evidence of pouch inflammation. First-morning stool concentration and total 24-hour calprotectin were quantified by use of a single step enzyme-linked immunosorbent assay. Biopsies from the reservoir were taken for conventional histology and scoring of intraepithelial neutrophil infiltrate. Cells positive for CD3, CD45RO, CD14, and CD15 within the lamina propria were quantified by use of immunohistochemistry., Results: The mean first-morning stool calprotectin concentration correlated with the 24-hour level (r = 0.91; P = <0.0001). The median single-stool calprotectin concentrations were 39 mg/l, 4 mg/l, and 8.5 mg/l (normal range, 0.2-10 mg/l) in patients with inflamed, noninflamed ulcerative colitis, and familial adenomatous polyposis, respectively. All nine patients with endoscopic and histologic evidence of pouch inflammation had raised stool calprotectin. Two of 15 patients without evidence of pouch inflammation had abnormal stool calprotectin. Single-stool calprotectin concentration correlated with the percentage of mature granulocytes (CD15; r = 0.46; P = 0.04) and activated macrophages (CD14; r = 0.65; P = 0.006), but not memory T cells (CD45RO; r = -0.05; P = 0.4) within the lamina propria., Conclusion: Single first-morning stool calprotectin levels provide a quantitative measure of pouch inflammation, which may be helpful in the diagnosis and assessment of pouchitis.
- Published
- 2000
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39. [Measurement of thyroid autoantibodies in Graves' disease.].
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Sigthorsson G, Olafsson O, and Kjeld M
- Abstract
It is thought that dietary iodine may play a role in thyroid autoimmune reactivity. Iceland is an iodine rich area and therefore it seemed interesting to measure autoantibodies against TSH receptor (TRAb), thyroid peroxidase (TPO) and thyroglobulin (TG) in Icelandic patients with Graves' disease. Serum samples were collected from 47 patients with untreated Graves' disease, 73 patients with Graves' disease that had been treated with radioiodine (U1I), most of them (56) hypothyroid following the treatment and therefore on T4 replacement, others euthyroid. Measurements were also done on samples from a reference group of 74 healthy volunteers. All reference values are 0.95 fractile. Untreated patients with Graves' disease had TRAb values over reference range in 68.1% of cases being similar to what others have observed. The untreated patients with Graves' disease had TPO antibody measurement positive in 50.0% of cases and TG antibodies in 34.7%. This is much lower frequency of positive tests than observed elsewhere when measured with ELISA. Although methodological factors might play a role, this difference could also be explained by difference in iodine intake. The antibodies were less frequent in radioiodine treated patients than in the untreated ones. This is in agreement with the observation that serum levels of these antibodies tend to decrease with time from treatment. The antibody measurements did not differentiate between radioiodine treated patients with Graves' disease needing T4 replacement and those who did not.
- Published
- 1996
40. [Results of individually adjusted radioiodine treatment of hyperthyroidism.].
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Sigthorsson G and Kjeld M
- Abstract
Radioiodine (131I) treatment was started in Iceland in 1960 and the same formula has been used from the beginning to calculate the doses of radioactivity aiming for 70 Gy irradiation of the gland. In the present investigation we studied 468 patients who were treated over a period of 19 years (1973-1991). About 90% of the patients had Graves' disease (GD), 9% toxic adenoma but less than 1% toxic multinodular goiter. Approximately 70% of the GD patients became hypothyroid (subclinical hypothyroidism included) within the first year after a single radioiodine treatment and about 80% were hypothyroid four years after treatment with no significant increase after that. By contrast, only one of 15 patients with toxic adenoma became hypothyroid after a single treatment. For both groups the recurrence rate of hyperthyroidism was approximately 20%. The formula used for dose calculation in this study for GD patients does not seem to be satisfactory. The smaller glands are getting to much irradiation and the larger glands to little as can be seen by the frequency of hypothyroidism in the smaller glands and recurrences (continuing hyperthyroidism) in the larger glands after one treatment (table V). In 1993 blood samples were obtained from a sample group (n=103) of once 131I treated GD patients and measurements were done for serum TSH, T4 and free T4. One third of the patients who were considered euthyroid, and therefore not taking T4, were found to be hypothyroid with elevated TSH and low FT4 and one third of those taking T4 seemed to be overtreated with elevated FT4 and decreased TSH levels. It is concluded that the results of the radioiodine treatment for GD are unsatisfactory and need to be changed, either by adjusting the present regimen so that radiation is decreased in the smaller glands but increased in the larger ones or alternatively, by increasing the radiation dose to all the glands rendering the majority of the patients quickly hypothyroid followed by replacement therapy. The follow up of patients could be improved.
- Published
- 1995
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