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Andrew Szilagyi - One of the best experts on this subject based on the ideXlab platform.
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meta analysis the diagnostic accuracy of Lactose breath hydrogen or Lactose Tolerance tests for predicting the north european lactase polymorphism c t 13910
Alimentary Pharmacology & Therapeutics, 2012Co-Authors: A Marton, Xiaoqing Xue, Andrew SzilagyiAbstract:Aliment Pharmacol Ther 2012; 35: 429–440 Summary Background The diagnostic accuracy of two indirect tests of Lactose digestion, Lactose breath hydrogen and Lactose Tolerance tests, have not been systematically reviewed for comparison with available publications on genotype. Aim To perform a meta-analysis of available studies that compares the north-European genetic polymorphism C/T-13910 with the Lactose breath hydrogen and the Lactose Tolerance tests, to determine their ability to predict geno/phenotype relationships. We examine the effects of Lactose loading dose, inclusion of children and latitudes of study centre on comparative outcome. Methods An electronic database of the literature as well as individual references in articles were searched with the theme of genetics of lactase and comparisons with breath or Lactose Tolerance tests were carried out. Random effect and fixed effect models were used for breath and Lactose Tolerance tests respectively, to report summary accuracy measures with 95% confidence intervals (CI). Results The search revealed 19 studies: 17 evaluated breath hydrogen, five Lactose Tolerance test (3/17 overlapped). Overall sensitivity was 0.88 (CI, 0.85–0.90), specificity was 0.85 (CI, 0.82–0.87) for breath test. Heterogeneity was explored by adjusting for studies including children, high or low dose Lactose and to some extent by site of study. The Lactose Tolerance test showed sensitivity of 0.94 (0.9–0.97) and specificity of 0.90 (0.84–0.95) with a nonsignificant heterogeneity. Conclusion The diagnostic accuracy of both tests individually reflects expected geno/phenotypes when the populations are well defined.
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comparison of a real time polymerase chain reaction assay for lactase genetic polymorphism with standard indirect tests for Lactose maldigestion
Clinical Gastroenterology and Hepatology, 2007Co-Authors: Andrew Szilagyi, Xiaoqing Xue, Paula Malolepszy, Elise Hamard, Nir Hilzenrat, Mary Ponniah, Elizabeth Macnamara, George ChongAbstract:Background & Aims: There is a discrepancy in outcome between the Lactose Tolerance and breath hydrogen tests for Lactose maldigestion. The availability of a validated genetic test for lactase polymorphism allows a reevaluation of these tests. Methods: Thirty healthy adults participated in a 50-g Lactose challenge test at a university clinic. Blood was drawn for genetic and timed blood glucose testing (2 hours), and breath hydrogen was measured (4.5 hours). Lactase genetic polymorphism was assessed by a real-time polymerase chain reaction assay. Participants completed a diet questionnaire, and symptoms were recorded during the Lactose challenge. Sensitivity and specificity were calculated for each indirect test. The 2-way kappa coefficient between these tests was evaluated. Student t test and Wilcoxon rank sum test were used to compare variables. Results: The Lactose Tolerance test as a standard had an 87.5% sensitivity and 92.7% specificity for genetic status. Only a moderate agreement between Lactose Tolerance test and breath hydrogen test was observed (2-way kappa coefficient, .53; 95% confidence interval, .22–.83). When genetic status was used as standard, symptoms had a moderate sensitivity and specificity. Lactose Tolerance test had very good sensitivity, and the breath test had excellent specificity. Conclusions: Both indirect tests independently have good to very good sensitivities and specificities for genetic lactase status. The noted disagreement likely reflects variables that affect the tests independently of intestinal lactase status. The value of these tests in the light of the availability of genetic testing is discussed.
Riitta Korpela - One of the best experts on this subject based on the ideXlab platform.
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Lactose inTolerance associated with adjuvant 5 fluorouracil based chemotherapy for colorectal cancer
Clinical Gastroenterology and Hepatology, 2004Co-Authors: Pia Osterlund, Katri Peuhkuri, Riitta Korpela, Tarja Ruotsalainen, Anneli Ollus, Minna Ikonen, Heikki Joensuu, Inkeri ElomaaAbstract:Abstract Background & Aims: Bowel mucosal injury associated with 5-fluorouracil (5-FU) treatment might result in secondary Lactose inTolerance. The frequency and clinical significance of 5-FU-related hypolactasia are unknown. Methods: One hundred fifty patients randomly assigned to receive 1 of 2 adjuvant 5-FU-based chemotherapy regimens, the Mayo regimen or the simplified de Gramont regimen, were studied for Lactose Tolerance by using an oral Lactose absorption test, a symptom questionnaire, treatment-related toxicity, and Subjective Global Assessment of Nutritional Status questionnaire before, during, and 2 and 6 months after chemotherapy for colorectal cancer. Results: The frequency of hypolactasia increased from 24% before treatment to 35% during treatment ( P P = 0.006). The presence of hypolactasia during chemotherapy was associated with flatulence, diarrhea, and poor nutritional status. Conclusions: Reversible chemotherapy-related hypolactasia and Lactose inTolerance are not infrequent in patients treated with 5-FU-based adjuvant chemotherapy for colorectal cancer. Avoidance of Lactose during chemotherapy may improve treatment tolerability in these patients.
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temperature of a test solution influences abdominal symptoms in Lactose Tolerance tests
Scandinavian Journal of Clinical & Laboratory Investigation, 2000Co-Authors: Katri Peuhkuri, Heikki Vapaatalo, R Nevala, Riitta KorpelaAbstract:In Lactose maldigesters, retarding gastric emptying (food/pharmaceuticals) improves Tolerance to Lactose. The role of temperature of test solution on the indicators of Lactose inTolerance was studied. After an overnight fast, 10 Lactose maldigesters ingested, in three sessions, 50 g Lactose in a randomized cross-over trial. The solutions were at temperatures of 20-21 degrees C (room temperature), 2-3 degrees C (cold) and 55-58 degrees C (hot). Gastrointestinal symptoms and indicators measuring Lactose absorption were recorded. Abdominal pain was noticeably increased by the modification of temperature. The cold solution reduced flatulence and abdominal bloating, whereas the hot solution increased bloating and borborygmi. Breath hydrogen excretion tended to be augmented and retarded after cold solution. The temperature of the solution used in a Lactose Tolerance test affects the gastrointestinal symptoms, but has only minor effects on the other indicators of Lactose maldigestion. The constant tendencies observed suggest that a room temperature solution is to be recommended for testing Lactose digestion.
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Wide variations in the testing of Lactose Tolerance: results of a questionnaire study in Finnish health care centres.
Scandinavian journal of clinical and laboratory investigation, 2000Co-Authors: Katri Peuhkuri, Heikki Vapaatalo, Riitta KorpelaAbstract:About 70% of the world's adult population is unable to digest Lactose, the sugar found naturally only in milk. This disability leads to gastrointestinal symptoms called Lactose inTolerance. In Finland, many patients visit health care centres because they are suffering from gastrointestinal symptoms. A few of them are diagnosed as being Lactose intolerant. However, a far larger number diagnose themselves as suffering from Lactose inTolerance. Therefore the diagnostic tests used should be carefully validated and standardized in clinical laboratories throughout the country. The aim of this questionnaire study was to clarify the situation centres with adult patients in Finnish health care and to try to standardize procedures for administering Lactose Tolerance tests.
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ibuprofen augments gastrointestinal symptoms in Lactose maldigesters during a Lactose Tolerance test
Alimentary Pharmacology & Therapeutics, 1999Co-Authors: Katri Peuhkuri, Heikki Vapaatalo, R Nevala, Eeva Moilanen, Riitta KorpelaAbstract:Background : Clinical symptoms during Lactose Tolerance test mimic those seen after therapeutic administration of prostaglandins, and resemble inflammatory processes. Aim : To investigate the possibility that Lactose-induced gastrointestinal symptoms are associated with prostaglandins and/or nitric oxide. Methods : After an overnight fast, nine maldigesters ingested Lactose or sucrose with or without an inhibitor of prostaglandin synthesis (ibuprofen), in a randomised double-blind crossover trial. Gastrointestinal symptoms, concentrations of PGE2-M in blood and urine, and urinary 6-keto PGF1α (as indicators of prostaglandin synthesis), and urinary nitrate and nitrite as well as cyclic GMP excretions (as indicators of nitric oxide formation), were measured. Results : Ibuprofen increased the first 3-h symptom scores (flatulence + borborygmi + abdominal bloating + pain) caused by Lactose (P=0.008) but not sucrose. The concentrations of PGE2-M in the plasma and in the urine were unaffected. Lactose increased the urinary excretion of 6-keto PGF1α by about 30% (P=0.17), which was inhibited by ibuprofen (P=0.02). The production of nitric oxide was unaffected by Lactose or ibuprofen. Conclusion : The inhibition of prostaglandin synthesis intensified gastrointestinal symptoms in Lactose maldigesters, suggesting a negligible role for prostanoids in Lactose-induced symptoms.
Piero Vernia - One of the best experts on this subject based on the ideXlab platform.
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diagnosis of Lactose inTolerance and the nocebo effect the role of negative expectations
Digestive and Liver Disease, 2010Co-Authors: Piero Vernia, Mauro Di Camillo, Tiziana Foglietta, Veronica E Avallone, Aurora De CarolisAbstract:Abstract Background Diagnosis of Lactose inTolerance is based on a “positive” H2 breath test associated with abdominal symptoms. The present study established to what extent the occurrence of symptoms during a “negative” H2 breath test may result from a “nocebo effect” instead of lack of sensitivity of the procedure. Methods Between 2005 and 2007, 636 outpatients performed a standard 4-h 25 g Lactose Tolerance test. The test was positive in 254, negative in 325, and 57 patients were H2 “non-producers”. Twenty-seven patients reporting symptoms despite a negative H2 breath test underwent a “sham” breath test following ingestion of 1 g of glucose. Fifty-four patients presenting with documented Lactose inTolerance were used as controls. Results Twelve out of 27 patients (44.4%), and unexpectedly also 14 (25.9%) controls presented abdominal symptoms during the sham test. The difference between the two groups was not significant (P Conclusion In most instances, symptoms reported by patients during a negative Lactose H2BT cannot be attributed to a false-negative test. Instead, a non-organic component, resulting from negative expectations (“nocebo effect”) is likely implicated. Moreover, also in patients diagnosed as Lactose intolerant, the need for restricting the primary source of dietary calcium should be critically reconsidered.
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hydrogen breath test for the diagnosis of Lactose inTolerance is the routine sugar load the best one
World Journal of Gastroenterology, 2008Co-Authors: Fiorenza Argnani, Mauro Di Camillo, Vanessa Marinaro, Tiziana Foglietta, Veronica E Avallone, Carlo Cannella, Piero VerniaAbstract:AIM: To evaluate the prevalence of Lactose inTolerance (LI) following a load of 12.5 g in patients diagnosed as high-grade malabsorbers using the hydrogen breath test (HBT)-25. METHODS: Ninety patients showing high-grade malabsorption at HBT-25 were submitted to a second HBT with a Lactose load of 12.5 g. Peak hydrogen production, area under the curve of hydrogen excretion and occurrence of symptoms were recorded. RESULTS: Only 16 patients (17.77%) with positive HBT-25 proved positive at HBT-12.5. Hydrogen production was lower as compared to HBT-25 (peak value 21.55 parts per million (ppm) ± 29.54 SD vs 99.43 ppm ± 40.01 SD; P < 0.001). Symptoms were present in only 13 patients. The absence of symptoms during the high-dose test has a high negative predictive value (0.84) for a negative low-dose test. The presence of symptoms during the first test was not useful for predicting a positive low-dose test (positive predictive value 0.06-0.31). CONCLUSION: Most patients with a positive HBT-25 normally absorb a lower dose of Lactose and a strict Lactose restriction on the basis of a “standard” HBT is, in most instances, unnecessary. Thus, the 25 g Lactose Tolerance test should probably be substituted by the 12.5 g test in the diagnosis of LI, and in providing dietary guidelines to patients with suspected Lactose malabsorption/inTolerance.
Maximilian Ledochowski - One of the best experts on this subject based on the ideXlab platform.
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hydrogen breath testing versus lct genotyping for the diagnosis of Lactose inTolerance a matter of age
Clinica Chimica Acta, 2007Co-Authors: Michaela Kerber, Christian Oberkanins, Gernot Kriegshauser, Barbara Kollerits, Astrid Dossenbachglaninger, Dietmar Fuchs, Maximilian LedochowskiAbstract:Abstract Background Two single nucleotide polymorphisms (-13910 C/T and -22018 G/A) upstream of the lactase gene (LCT) have been found to be associated with Lactose Tolerance in Europeans. Methods In one hundred and twenty Austrian outpatients, who visited the physician's office for symptoms of irritable bowel syndrome (IBS), hydrogen breath testing (HBT) and LCT genotyping by polymerase chain reaction and reverse-hybridisation were performed in parallel. Results The coincidence between a genotype suggesting lactase non-persistence (Lactose inTolerance) and a positive HBT result was almost perfect (97.4% for LCT-13910 C/T and 100% for LCT-22018 G/A). Between a genotype indicating lactase persistence (Lactose Tolerance) and a negative HBT result the coincidence was lower (72% and 71.4%, respectively). Among heterozygotes, there was a statistically significant increase in the proportion of positive HBT results with age. Both SNPs were in accordance in 117/120 (97.5%) patients. Conclusion Genetic analysis of LCT-13910 C/T and LCT-22018 G/A is a good indicator for the presence of Lactose inTolerance. Because age, as well as a number of secondary causes (e.g. celiac disease), can influence HBT results, it is useful to combine HBT and genetic analysis in the diagnostic assessment of IBS.
Neil Bradman - One of the best experts on this subject based on the ideXlab platform.
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Diversity of lactase persistence alleles in Ethiopia: signature of a soft selective sweep.
American journal of human genetics, 2013Co-Authors: Bryony L. Jones, Tamiru Oljira Raga, Endashaw Bekele, Neil Bradman, Anke Liebert, Pawel Zmarz, E. Thomas Danielsen, Anders Krüger Olsen, Jesper T. Troelsen, Dallas M. SwallowAbstract:The persistent expression of lactase into adulthood in humans is a recent genetic adaptation that allows the consumption of milk from other mammals after weaning. In Europe, a single allele (−13910∗T, rs4988235) in an upstream region that acts as an enhancer to the expression of the lactase gene LCT is responsible for lactase persistence and appears to have been under strong directional selection in the last 5,000 years, evidenced by the widespread occurrence of this allele on an extended haplotype. In Africa and the Middle East, the situation is more complicated and at least three other alleles (−13907∗G, rs41525747; −13915∗G, rs41380347; −14010∗C, rs145946881) in the same LCT enhancer region can cause continued lactase expression. Here we examine the LCT enhancer sequence in a large Lactose-Tolerance-tested Ethiopian cohort of more than 350 individuals. We show that a further SNP, −14009T>G (ss 820486563), is significantly associated with Lactose-digester status, and in vitro functional tests confirm that the −14009∗G allele also increases expression of an LCT promoter construct. The derived alleles in the LCT enhancer region are spread through several ethnic groups, and we report a greater genetic diversity in Lactose digesters than in nondigesters. By examining flanking markers to control for the effects of mutation and demography, we further describe, from empirical evidence, the signature of a soft selective sweep.
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A novel polymorphism associated with Lactose Tolerance in Africa: multiple causes for lactase persistence?
Human genetics, 2006Co-Authors: Catherine J. E. Ingram, Mark G. Thomas, Charlotte A. Mulcare, Mohamed F. Elamin, Michael E. Weale, Ayele Tarekegn, Tamiru Oljira Raga, Endashaw Bekele, Farouk M. Elamin, Neil BradmanAbstract:Persistence or non-persistence of lactase expression into adult life is a polymorphic trait that has been attributed to a single nucleotide polymorphism (C-13910T) in an enhancer element 13.9 kb upstream of the lactase gene (LCT). The -13910*T allele occurs at very high frequency in northern Europeans as part of a very long haplotype (known as A), and promotes binding of the transcription factor Oct-1. However, -13910*T is at very low frequency in many African milk drinking pastoralist groups where lactase persistence phenotype has been reported at high frequency. We report here for the first time, a cohort study of Lactose digester and non-digester Sudanese volunteers and show there is no association of -13910*T or the A haplotype with lactase persistence. We support this finding with new genotype/phenotype frequency comparisons in pastoralist groups of eastern African and Middle Eastern origin. Resequencing revealed three new SNPs in close proximity to -13910*T, two of which are within the Oct-1 binding site. The most frequent of these (-13915*G) is associated with Lactose Tolerance in the cohort study, providing evidence for a cis-acting effect. Despite its location, -13915*G abolishes, rather than enhances Oct-1 binding, indicating that this particular interaction is unlikely to be involved in lactase persistence. This study reveals the complexity of this phenotypic polymorphism and highlights the limitations of C-13910T as a diagnostic test for lactase persistence status, at least for people with non-European ancestry.
