| 1. |
- Nilsson, Mats, et al.
(author)
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Medical intelligence in Sweden. Vitamin B12 : oral compared with parenteral?
- 2005
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In: Postgraduate medical journal. - : Oxford University Press (OUP). - 0032-5473 .- 1469-0756. ; 81:953, s. 191-193
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Journal article (peer-reviewed)abstract
- BACKGROUND: Sweden is the only country in which oral high dose vitamin B12 has gained widespread use in the treatment of deficiency states. OBJECTIVE: The aim of the study was to describe prescribing patterns and sales statistics of vitamin B12 tablets and injections in Sweden 1990-2000.Design, setting, and sources: Official statistics of cobalamin prescriptions and sales were used. RESULTS: The use of vitamin B12 increased in Sweden 1990-2000, mainly because of an increase in the use of oral high dose vitamin B12 therapy. The experience, in statistical terms a "total investigation", comprised 1,000,000 patient years for tablets and 750,000 patient years for injections. During 2000, 13% of residents aged 70 and over were treated with vitamin B12, two of three with the tablet preparation. Most patients in Sweden requiring vitamin B12 therapy have transferred from parenteral to oral high dose vitamin B12 since 1964, when the oral preparation was introduced. CONCLUSION: The findings suggest that many patients in other post-industrial societies may also be suitable for oral vitamin B12 treatment.
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| 2. |
- Söderberg, Johan, 1980-, et al.
(author)
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Haemolysis index : an estimate of preanalytical quality in primary health care!
- 2009
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In: Clinical Chemistry and Laboratory Medicine. - 1434-6621 .- 1437-4331. ; 47:8, s. 940-944
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Journal article (peer-reviewed)abstract
- Background: Haemolysis is usually caused by inadequate specimen collection or preanalytical handling, and is suggested to be a suitable indicator of preanalytical quality. We investigated the prevalence of detectable haemolysis in all routine venous blood samples to identify differences in preanalytical quality.Methods: Haemolysis index (HI) values were obtained from a Vitros 5,1 in the routine clinical chemistry laboratory for samples collected in primary health care centres (PHCs), nursing homes, and a hospital emergency department (ED). Haemolysis was defined as a HI ≥ 15 (detection limit).Results: Samples from the PHC with the highest prevalence of haemolysis were 6.1 times (95% confidence interval (CI) 4.0-9.2) more often haemolysed compared to the centre with the lowest prevalence. Of the samples collected in primary health care, 10.4% were haemolysed compared to 31.1% in the ED (p< 0.001). A notable difference in haemolysed samples was found between the ED section staffed by emergency medicine physicians and the section staffed by primary health care physicians (34.8% vs. 11.3%, p<0.001).Conclusions: The significant variation in haemolysis indices among the investigated units is likely to reflect varying preanalytical conditions. The HI is a valuable tool for estimation and follow-up of preanalytical quality in primary health care.
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| 3. |
- Wallin, Olof, et al.
(author)
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Preanalytical effects of pneumatic tube transport on routine haematology, coagulation parameters, platelet function and global coagulation
- 2009
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In: Clinical Chemistry and Laboratory Medicine. - 1434-6621 .- 1437-4331. ; 46:10, s. 1443-1449
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Journal article (peer-reviewed)abstract
- Background: Pneumatic tube transport of blood samples reduces turnaround times and labour. However, the preanalytical effects on new clinical chemistry parameters and instruments are not fully known. The aim of this study was to evaluate the effect of pneumatic tube transport on haematology and coagulation parameters, including platelet function with PFA-100®, and global coagulation with a thromboelastograph.Methods: Paired venous blood samples from healthy volunteers were obtained before and after 1 week of treatment with acetylsalicylic acid. One sample was transported by pneumatic tube transport, while the other remained in the laboratory.Results: No preanalytical effect of pneumatic tube transport could be seen for most haematology and coagulation parameters, as well as analysis with PFA-100®. For the thromboelastographic analysis, time to clot formation was shorter (–16%, p=0.037) in the transported samples. Treatment with acetylsalicylic acid had no effect on the majority of the test results.Conclusions: Pneumatic tube transport does not introduce preanalytical errors when transporting samples for analysis of routine haematology, coagulation parameters and platelet function with the PFA-100®. We recommend manual transport of samples for analysis with thromboelastographic techniques.
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| 4. |
- Arslan, Alan A, et al.
(author)
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Circulating vitamin d and risk of epithelial ovarian cancer
- 2009
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In: Journal of oncology. - : Hindawi Limited. - 1687-8450 .- 1687-8469. ; 2009, s. 672492-672500
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Journal article (peer-reviewed)abstract
- We conducted a nested case-control study within two prospective cohorts, the New York University Women's Health Study and the Northern Sweden Health and Disease Study, to examine the association between prediagnostic circulating levels of 25-hydroxy vitamin D (25(OH)D) and the risk of subsequent invasive epithelial ovarian cancer (EOC). The 25(OH)D levels were measured in serum or plasma from 170 incident cases of EOC and 373 matched controls. Overall, circulating 25(OH)D levels were not associated with the risk of EOC in combined cohort analysis: adjusted OR for the top tertile versus the reference tertile, 1.09 (95% CI, 0.59-2.01). In addition, there was no evidence of an interaction effect between VDR SNP genotype or haplotype and circulating 25(OH)D levels in relation to ovarian cancer risk, although more complex gene-environment interactions may exist.
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| 5. |
- Dahlin, Anna M, 1979-, et al.
(author)
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Plasma vitamin B12 concentrations and the risk of colorectal cancer : a nested case-referent study
- 2008
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In: International Journal of Cancer. - : Wiley. - 0020-7136 .- 1097-0215. ; 32:2, s. 304-314
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Journal article (peer-reviewed)abstract
- In this nested case-referent study, we related plasma concentrations of vitamin B12 to the risk of colorectal cancer, taking into consideration prediagnostic plasma folate and total homocysteine concentrations. Subjects were 226 cases and double matched referents from the population-based Northern Sweden Health and Disease Study. Follow-up times from recruitment to diagnosis ranged from 0.1 to 12.7 years, with a median of 4.2 years. Plasma vitamin B12 concentrations were inversely associated with the risk of rectal cancer: univariate odds ratio for the highest versus lowest quintile 0.34 (95% confidence interval (95% CI) 0.13-0.83), p(trend) = 0.004. Risk estimates were attenuated slightly but remained statistically significant after adjustment for body mass index, current smoking, recreational and occupational physical activity, alcohol intake and prediagnostic plasma folate and total homocysteine concentrations: OR 0.30 (95% CI 0.08-0.99), p(trend) = 0.025. The corresponding univariate and fully adjusted odds ratios for colon cancer were 1.25 (CI 0.66-2.36), p(trend) = 0.185 and 1.42 (CI 0.67-3.05), p(trend) = 0.113, respectively. The observed over-risk was attributable to left-sided colon cancer. Interaction analyses including vitamin B12, folate and homocysteine were in line with the results for vitamin B12 alone. In conclusion, these results suggest that increasing levels of plasma vitamin B12, alone or together with other factors involved in one-carbon metabolism, may reduce the risk of rectal cancer, whereas for colon cancer, the association appears to be less clear.
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| 6. |
- Ekblom, Kim, 1970-, et al.
(author)
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Iron stores and HFE genotypes are not related to increased risk of ischemic stroke. : a prospective nested case-referent study
- 2007
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In: Cerebrovascular Diseases. - : S. Karger AG. - 1015-9770 .- 1421-9786. ; 24:5, s. 405-411
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Journal article (peer-reviewed)abstract
- Background: High iron levels can increase the formation of noxious oxygen radicals, which are thought to contribute to cerebrovascular disease. The aim of this prospective study was to determine if iron status and HFE genotypes constitute risk factors for stroke. Methods: First-ever stroke cases (231 ischemic and 42 hemorrhagic) and matched double referents from the population-based Northern Sweden cohorts were studied in a nested case-referent setting. Results: For total iron binding capacity, an increased risk of ischemic stroke was seen in the highest quartile (OR 1.80; 95% CI 1.14-2.83; p for trend 0.012). The highest quartile of transferrin iron saturation showed a decreased risk of ischemic stroke in men (OR 0.44; 95% CI 0.22-0.87; p for trend 0.028), but not in women. There was an increased risk of hemorrhagic stroke in the second (OR 4.07; 95% CI 1.09-15.20) and third quartile (OR 4.22; 95% CI 1.08-16.42) of ferritin. Neither quartiles of plasma iron concentrations nor the HFE C282Y and H63D genotypes were associated with ischemic or hemorrhagic stroke. Conclusions: Iron stores were not positively related to increased risk of ischemic stroke. Furthermore, HFE genotypes did not influence the risk of ischemic or hemorrhagic stroke. Copyright (c) 2007 S. Karger AG, Basel.
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| 7. |
- Eklöf, Vincy, et al.
(author)
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The reduced folate carrier (RFC1) 80G>A and folate hydrolase 1 (FOLH1) 1561C>T polymorphisms and the risk of colorectal cancer : a nested case-referent study
- 2008
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In: Scandinavian Journal of Clinical and Laboratory Investigation. - : Informa UK Limited. - 0036-5513 .- 1502-7686. ; 68:5, s. 393-401
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Journal article (peer-reviewed)abstract
- Objective. Polymorphisms in genes involved in folate uptake and metabolism may affect folate status and, thereby, the risk of cancer. In this nested case‐referent study, we related two such polymorphisms, reduced folate carrier (RFC1) 80G>A and folate hydrolase 1 (FOLH1) 1561C>T, to the risk of colorectal cancer, taking into account pre‐diagnostic plasma folate and total homocysteine concentrations and the MTHFR 677C>T polymorphism, which were analysed in a previous study.Material and methods. Subjects were 220 cases and 414 matched referents from the population‐based Northern Sweden Health and Disease Study.Results. The RFC1 80A‐allele was associated with reduced plasma folate and elevated plasma total homocysteine concentrations, but the result was statistically significant only for folate. In contrast, the FOLH1 1561T‐allele was associated with higher plasma folate and reduced plasma total homocysteine concentrations, and the result was statistically significant only for homocysteine. Neither polymorphism was related to the risk of colorectal cancer, either in univariate analysis or after adjusting for body mass index, current smoking, recreational and occupational physical activity and alcohol intake. Further adjustment for folate or homocysteine status or the MTHFR 677C>T polymorphism did not affect risk estimates. Subjects with the RFC1 80AA genotype in combination with low plasma folate concentrations or the MTHFR 677TT genotype had a reduced risk of colorectal cancer of borderline statistical significance.Conclusions. These findings suggest that although the RFC1 80G>A and FOLH1 1561C>T polymorphisms may influence folate status, they are not likely to have a major independent role in the development of colorectal cancer.Read More: http://informahealthcare.com/doi/abs/10.1080/00365510701805431
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| 8. |
- Hultdin, Johan, 1964-
(author)
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Homocysteine in cardiovascular disease with special reference to longitudinal changes
- 2005
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Doctoral thesis (other academic/artistic)abstract
- Abnormalities in homocysteine metabolism have been suggested as risk factors for stroke and myocardial infarction. In retrospective studies, elevated levels of total plasma homocysteine (tHcy) and/or methylenetetrahydrofolate reductase (MTHFR) 677C>T polymorphism have indicated an increase in risk. However, the fewer prospective studies have not been as conclusive. To further explore this, tHcy was studied in four prospective settings. The first was a prospective nested case-referent cohort within the Västerbotten Intervention Program (VIP) and WHO MONICA project on 312 ischemic and 60 haemorrhagic first-ever strokes. The aim was to study tHcy and its main genetic determinant MTHFR. Risk for haemorrhagic stroke increased exponentially through tHcy quartiles, independent of hypertension and BMI, and increased for MTHFR 677 CT and TT. MTHFR 1298A>C appeared to be protective. In multivariate models, after adjustment for tHcy, BMI and hypertension, both tHcy and MTHFR remained as independent predictors for hemorrhagic stroke. Neither tHcy, nor the two MTHFR polymorphisms were significant predictors for ischemic strokes. The second was a prospective long-term follow-up study within the VIP and MONICA cohorts to determine whether a first-ever myocardial infarction (AMI) causes increased levels of tHcy. Fifty cases developing AMI after the first screening participated in a second screening (mean follow-up 8.5 years) with 56 matched referents. Increase in tHcy did not differ between cases and referents. tHcy was related to AMI at follow-up, but not at baseline and no longer significant after adjusting for creatinine and albumin. The third was a method study to determine if cystatin C, creatinine, albumin and other lipoprotein risk markers of cardiovascular disease could be analysed in Stabilyte™ plasma stored at -80°C. It was found to be suitable for all analyses tested and using this tube would simplify sampling for epidemiological studies. The fourth study was a prospective longitudinal long-term study of 735 subjects (340 men and 395 women, age 25-64 at first screening), participating in two MONICA screenings nine years apart, who donated blood in Stabilyte™ tubes to study change over time in tHcy and its determinants. We confirmed the age dependency in a cross sectional setting. In contrast, if followed longitudinally over time, no change in tHcy or in the prevalence of hyperhomocysteinemia was found. Cystatin C and creatinine increased, and albumin decreased. In multivariate models baseline levels of albumin, creatinine, cystatin C, and to some extent hs-CRP, were predictors of tHcy at follow-up but gender differences were seen. Age was not a major determinant of change in tHcy over nine years. In conclusion, tHcy and MTHFR are risk factors for first-ever haemorrhagic, but not ischemic stroke in a prospective setting. A first myocardial infarction does not cause an increase in tHcy. No long-term changes were seen in tHcy over a nine-year period in neither men, nor in women.
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| 9. |
- Hultdin, Johan, et al.
(author)
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Plasma folate, vitamin B12, and homocysteine and prostate cancer risk : a prospective study.
- 2005
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In: International Journal of Cancer. - : Wiley. - 0020-7136 .- 1097-0215. ; 113:5, s. 819-824
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Journal article (peer-reviewed)abstract
- The role of folate metabolism in cancer development is a topic of much current interest, with maintenance of adequate folate status tending to show a protective effect. Aberrant methylation, primarily hypermethylation of certain genes including tumor suppressors, has been implicated in prostate cancer development. Folate, vitamin B12 and homocysteine are essential for methyl group metabolism and thus also for DNA methylation. We related plasma levels of these factors to prostate cancer risk in a prospective study of 254 case subjects and 514 matched control subjects. Increasing plasma levels of folate and vitamin B12 were statistically significantly associated with increased prostate cancer risk, with an odds ratio of 1.60 (95% CI = 1.03-2.49; p(trend) = 0.02) for folate and 2.63 (95% CI = 1.61-4.29; p(trend) < 0.001) for vitamin B12 for highest vs. lowest quartile. Increasing plasma homocysteine levels were associated with a reduced risk of borderline significance (OR = 0.67; 95% CI = 0.43-1.04; p(trend) = 0.08). After adjustment for the other 2 plasma variables, body mass index and smoking, a statistically significant increased risk remained only for vitamin B12 (OR = 2.96; 95% CI = 1.58-5.55; p(trend) = 0.001). Adjusted OR for folate and homocysteine were 1.30 (95% CI = 0.74-2.24; p(trend) = 0.17) and 0.91 (95% CI = 0.51-1.58; p(trend) = 0.60), respectively. Our results suggest that factors contributing to folate status are not protective against prostate cancer. On the contrary, vitamin B12, associated with an up to 3-fold increase in risk, and possibly also folate, may even stimulate prostate cancer development. These findings are novel and should be explored further in future studies. (c) 2004 Wiley-Liss, Inc.
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| 10. |
- Johansson, Mattias, et al.
(author)
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One-carbon metabolism and prostate cancer risk : prospective investigation of seven circulating B vitamins and metabolites
- 2009
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In: Cancer Epidemiology, Biomarkers and Prevention. - 1055-9965 .- 1538-7755. ; 18:5, s. 1538-1543
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Journal article (peer-reviewed)abstract
- PURPOSE: Components of one-carbon metabolism are believed to influence cancer development with suggested mechanisms, including DNA methylation and DNA repair mechanisms. However, few prospective studies have investigated one-carbon metabolism in relation to prostate cancer risk, and the results have been conflicting. The aim of this study was to do a comprehensive investigation of the components of one-carbon metabolism in relation to prostate cancer risk. A panel of seven circulating B vitamins and related metabolites was selected, most of which have not been studied before. MATERIALS AND METHODS: We analyzed plasma concentrations of betaine, choline, cysteine, methionine, methylmalonic acid (MMA), vitamin B2, and vitamin B6 in 561 cases and 1,034 controls matched for age and recruitment date, nested within the population-based Northern Sweden Health and Disease Cohort. Relative risks of prostate cancer were estimated by conditional logistic regression. RESULTS: Positive associations with prostate cancer risk were observed for choline and vitamin B2, and an inverse association was observed for MMA. The relative risks for a doubling in concentrations were 1.46 [95% confidence interval (95% CI), 1.04-2.05; P(trend) = 0.03] for choline, 1.11 (95% CI, 1.00-1.23; P(trend) = 0.04) for vitamin B2, and 0.78 (95% CI, 0.63-0.97; P(trend) = 0.03) for MMA. Concentrations of betaine, cysteine, methionine, and vitamin B6 were not associated with prostate cancer risk. CONCLUSION: The results of this large prospective study suggest that elevated plasma concentrations of choline and vitamin B2 may be associated with an increased risk of prostate cancer. These novel findings support a role of one-carbon metabolism in prostate cancer etiology and warrant further investigation. (Cancer Epidemiol Biomarkers Prev 2009;18(5):1538-43).
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| 11. |
- Johansson, Mattias, et al.
(author)
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The MTHFR 677C --> T polymorphism and risk of prostate cancer : results from the CAPS study
- 2007
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In: Cancer Causes and Control. - Umea Univ Hosp, Dept Surg & Perioperat Sci, S-90185 Umea, Sweden. Univ Umea Hosp, Dept Med Biosci, S-90185 Umea, Sweden. Karolinska Inst, Dept Med Epidemiol & Biostat, Stockholm, Sweden. Harvard Univ, Dept Epidemiol, Cambridge, MA 02138 USA. : Springer Science and Business Media LLC. - 0957-5243 .- 1573-7225. ; 18:10, s. 1169-1174
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Journal article (peer-reviewed)abstract
- The methylenetetrahydrafolate reductase (MTHFR) enzyme may influence cancer development by affecting DNA methylation, synthesis and repair. The MTHFR 677C→T single nucleotide polymorphism (SNP) has been associated with decreased enzyme activity and has therefore been implicated in cancer development. We analyzed the MTHFR 677C→T SNP in 2,777 incident prostate cancer cases and 1,639 population controls from the CAncer Prostate in Sweden study (CAPS). No significant association was found overall between prostate cancer risk and the 677C→T SNP (p = 0.27) with heterozygote (CT) and homozygote (TT) allele carriers showing ORs of 1.12 (95% CI: 0.98–1.27) and 1.02 (95% CI: 0.80–1.30), respectively. In the subgroup of low risk prostate cancer, heterozygote—but not homozygote—allele carriers displayed a slight over-risk with an OR of 1.21 (95% CI: 1.03–1.41). Among men under 65 years of age, the 677C→T SNP was associated with prostate cancer risk (p = 0.007), with odds ratios of 1.33 (95% CI: 1.09–1.63) for heterozygote allele carriers and 0.86 (95% CI: 0.6–1.24) for homozygote allele carriers. However, this association was attributed to a shift in the genotype distribution in the young controls. In conclusion, our results do not provide strong support for the hypothesis that the MTHFR 677C→T polymorphism is related to prostate cancer risk.
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| 12. |
- Kivipelto, M, et al.
(author)
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Homocysteine and holo-transcobalamin and the risk of dementia and Alzheimers disease : a prospective study.
- 2009
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In: European journal of neurology : the official journal of the European Federation of Neurological Societies. - : Wiley. - 1468-1331 .- 1351-5101. ; 16:7, s. 808-813
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Journal article (peer-reviewed)abstract
- BACKGROUND: Elevated total homocysteine (tHcy) levels may be caused by vitamin B12 deficiency and are linked to Alzheimers disease (AD) in some studies, although the evidence is mixed. Another marker of vitamin B12 deficiency, holo-transcobalamin (holo-TC), has not been studied in a prospective setting. OBJECTIVE: To investigate the association between tHcy and holo-TC and the subsequent development of dementia and AD in a prospective study. METHODS: A sub-sample of 228 non-demented subjects was taken from the Kungsholmen Project, a population-based longitudinal study amongst persons 75+ years. tHcy and holo-TC were analysed at baseline. RESULTS: Increasing tHcy levels were related to an increased risk of dementia (n = 83) and AD (n = 61) after a mean follow-up time of 6.7 years. Persons with high tHcy (the fourth quartile) had more than twice as high a risk of developing AD than persons with low tHcy, even after adjusting for confounding or mediating factors. The third quartile of holo-TC was associated with a reduced risk of AD, after adjusting for Hcy and other confounders. CONCLUSIONS: These results suggest that Hcy is involved in the development of dementia and AD. The role of holo-TC was less clear and this marker needs to be studied further.
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| 13. |
- Samuelsson, Eva, et al.
(author)
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Ung kvinna med p-ring drabbad av armtrombos : möjligt samband med mutation i protrombingenen
- 2007
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In: Läkartidningen. - Stockholm : Sveriges läkarförbund. - 0023-7205 .- 1652-7518. ; 104:1-2, s. 32-34
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Journal article (other academic/artistic)abstract
- En ung kvinna fick en trombosi vena axillaris under p-ringanvändning. Trombosutredningpåvisade heterozygoti för 20210G>A i protrombingenen, en mutation som kan ha särskildbetydelse vid armtrombos.Incidensen av trombos under p-pilleranvändning beräknas till 2–4 fall per 10 000 användarår. Inget talar för att kombinerad hormonell antikonceptioni form av vaginal ring eller plåster innebär lägre risk förblodpropp. P-ringen marknadsförs med budskap om låga hormon nivåer, men betydelsen av detta är oklar, då den totala östrogeniteten är hög.Fyra fall av blodpropp under NuvaRing-användning i Sverigehar hittills rapporterats till biverkningsenheten. Ur rapporterna framgår det att pringen inte alltid uppfattas som ett systemiskt verkande hormonellt antikonceptions medel.
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| 14. |
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| 15. |
- Van Guelpen, Bethany, et al.
(author)
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Folate, vitamin B12, and risk of ischemic and hemorrhagic stroke: a prospective, nested case-referent study of plasma concentrations and dietary intake.
- 2005
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In: Stroke; a journal of cerebral circulation. - 1524-4628 .- 0039-2499. ; 36:7, s. 1426-31
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Journal article (peer-reviewed)abstract
- BACKGROUND AND PURPOSE: Folate metabolism has been implicated in stroke. However, the possibility of a role for folate and vitamin B12, independent of their effects on homocysteine status, remains to be explored. The aim of this prospective, nested case-referent study was to relate plasma and dietary intake levels of folate and vitamin B12 to risk of stroke, taking into consideration plasma homocysteine concentrations and methylenetetrahydrofolate reductase polymorphisms. METHODS: Subjects were 334 ischemic and 62 hemorrhagic stroke cases and matched double referents from the population-based Northern Sweden Health and Disease Cohort. RESULTS: Plasma folate was statistically significantly associated with risk of hemorrhagic stroke in an inverse linear manner, both in univariate analysis and after adjustment for conventional risk factors including hypertension (odds ratio [OR] for highest versus lowest quartile 0.21 (95% confidence interval [CI], 0.06 to 0.71; P for trend=0.008)). Risk estimates were attenuated by inclusion of homocysteine in the model (OR, 0.34; 95% CI, 0.08 to 1.40; P for trend=0.088). A similar pattern was observed for increasing folate intake (multivariate OR, 0.07; 95% CI, 0.01 to 0.55; P for trend=0.031 without homocysteine, and OR, 0.16, 95% CI, 0.02 to 1.23; P for trend=0.118 with homocysteine in the analysis). We found little evidence of an association between plasma or dietary folate and risk of ischemic stroke. Neither plasma nor dietary vitamin B12 was associated with risk of either stroke subtype. CONCLUSIONS: The results of this study suggest a protective role for folate, possibly in addition to its effects on homocysteine status, in hemorrhagic but not ischemic stroke.
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| 16. |
- Van Guelpen, Bethany, et al.
(author)
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Low folate levels may protect against colorectal cancer.
- 2006
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In: Gut. - : BMJ. - 0017-5749 .- 1468-3288. ; 55:10, s. 1461-6
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Journal article (peer-reviewed)abstract
- BACKGROUND AND AIMS: Dietary folate is believed to protect against colorectal cancer (CRC). However, few studies have addressed the role of circulating levels of folate. The aim of this study was to relate prediagnostic plasma folate and homocysteine concentrations and the methylenetetrahydrofolate reductase (MTHFR) 677C>T and 1298A>C polymorphisms to the risk of developing CRC. SUBJECTS: Subjects were 226 cases and 437 matched referents from the population based Northern Sweden Health and Disease Cohort. RESULTS: We observed a bell-shaped association between plasma folate concentrations and CRC risk; multivariate odds ratio for middle versus lowest quintile 2.00 (95% confidence interval (CI) 1.13-3.56). In subjects with follow up times greater than the median of 4.2 years however, plasma folate concentrations were strongly positively related to CRC risk; multivariate odds ratio for highest versus lowest quintile 3.87 (95% CI 1.52-9.87; p trend = 0.007). Homocysteine was not associated with CRC risk. Multivariate odds ratios for the MTHFR polymorphisms were, for 677 TT versus CC, 0.41 (95% CI 0.19-0.85; p trend = 0.062), and for 1298 CC versus AA, 1.62 (95% CI 0.94-2.81; p trend = 0.028). Interaction analysis suggested that the result for 1298A>C may have been largely due to linkage disequilibrium with 677C>T. The reduced CRC risk in 677 TT homozygotes was independent of plasma folate status. CONCLUSIONS: Our findings suggest a decreased CRC risk in subjects with low folate status. This possibility of a detrimental component to the role of folate in carcinogenesis could have implications in the ongoing debate in Europe concerning mandatory folate fortification of foods.
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| 17. |
- Van Guelpen, Bethany, et al.
(author)
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Plasma folate and total homocysteine levels are associated with the risk of myocardial infarction, independently of each other and of renal function.
- 2009
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In: Journal of internal medicine. - : Wiley. - 1365-2796 .- 0954-6820. ; 266:2, s. 182-95
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Journal article (peer-reviewed)abstract
- OBJECTIVES: To investigate the relationship between plasma folate, vitamin B12 and total homocysteine concentrations, dietary intake of folate and vitamins B12, B6 and B2, and the risk of first acute myocardial infarction (MI). DESIGN: Nested case-referent study with up to 13 years of follow-up. SETTING: The population-based Northern Sweden Health and Disease Study, with 73 879 participants at the time of case ascertainment. SUBJECTS: A total of 571 MI cases (406 men) and 1569 matched referents. Of the cases, 530 had plasma samples available, and 247 had dietary B-vitamin intake data. RESULTS: Plasma concentrations of folate were inversely associated, and total homocysteine positively associated, with the risk of MI, independently of each other and of a number of established and novel cardiovascular risk factors, including renal function [multivariate odds ratio for highest vs. lowest quintile of folate 0.52 (95% CI 0.31-0.84), P for trend = 0.036, and homocysteine 1.92 (95% CI 1.20-3.09), P for trend = 0.006]. For plasma vitamin B12 concentrations, and vitamin B12, B6 and B2 intake, no clear risk relationship was apparent. Though not statistically significant, the results for folate intake were consistent with those for plasma concentrations. CONCLUSIONS: In this large prospective study of a population without mandatory folic acid fortification, both folate and homocysteine were strongly associated with the risk of myocardial infarction, independently of each other and of renal function. Although randomized trials of folic acid supplementation are needed to determine causality, our findings highlight the potential importance of folate, or sources of folate, in incident cardiovascular disease.
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| 18. |
- Van Guelpen, Bethany, et al.
(author)
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Polymorphisms of methylenetetrahydrofolate reductase and the risk of prostate cancer : a nested case-control study
- 2006
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In: European Journal of Cancer Prevention. - : Lippincott Williams & Wilkins. - 0959-8278 .- 1473-5709. ; 15:1, s. 46-50
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Journal article (peer-reviewed)abstract
- It has been proposed that folate and polymorphisms of the enzyme methylenetetrahydrofolate reductase (MTHFR), which regulates influx of folate from DNA synthesis and repair to methylation reactions, are involved in the aetiology of cancer. To relate the MTHFR 677C→T and 1298A→C polymorphisms to the risk of prostate cancer, taking into consideration prospective plasma levels of folate, vitamin B12 and homocysteine. The design was a case-control study of 223 prostate cancer cases and 435 matched controls nested within the population-based Northern Sweden Health and Disease Cohort. Neither the MTHFR 677C→T nor the MTHFR 1298A→C polymorphism was statistically significantly associated with the risk of prostate cancer in univariate analysis by conditional logistic regression. After adjustment for MTHFR 1298A→C, plasma folate, vitamin B12, homocysteine, body mass index and smoking, the odds ratios were, for the 677 CT genotype, 1.52 [95% confidence interval (CI) 1.02-2.26], and for TT, 0.91 (95% CI 0.41-2.04). Our previously reported observation of a possible increase in the risk of prostate cancer at high plasma folate levels was attributable in this study to subjects having the MTHFR 677C→T polymorphism. We found that the MTHFR 677C→T polymorphism is not likely to have a major role in the development of prostate cancer, although it may possibly increase the risk in combination with high plasma folate levels. Further investigation in larger studies is warranted.
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| 19. |
- Wallin, Olof, 1976-
(author)
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Preanalytical errors in hospitals : implications for quality improvement of blood sample collection
- 2008
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Doctoral thesis (other academic/artistic)abstract
- Background: Most errors in the venous blood testing process are preanalytical, i.e. they occur before the sample reaches the laboratory. Unlike the laboratory analysis, the preanalytical phase involves several error-prone manual tasks not easily avoided with technological solutions. Despite the importance of the preanalytical phase for a correct test result, little is known about how blood samples are collected in hospitals. Aim: The aim of this thesis was to survey preanalytical procedures in hospitals to identify sources of error. Methods: The first part of this thesis was a questionnaire survey. After a pilot study (Paper I), a questionnaire addressing clinical chemistry testing was completed by venous blood sampling staff (n=314, response rate 94%) in hospital wards and hospital laboratories (Papers II–IV). The second part of this thesis was an experimental study. Haematology, coagulation, platelet function and global coagulation parameters were compared between pneumatic tube-transported samples and samples that had not been transported (Paper V). Results: The results of the questionnaire survey indicate that the desirable procedure for the collection and handling of venous blood samples were not always followed in the wards (Papers II–III). For example, as few as 2.4% of the ward staff reported to always label the test tube immediately before sample collection. Only 22% of the ward staff reported to always use wristbands for patient identification, while 18% reported to always use online laboratory manuals, the only source of updated information. However, a substantial part of the ward staff showed considerable interest in re-education (45%) and willingness to improve routines (44%) for venous blood sampling. Compared to the ward staff, the laboratory staff reported significantly higher proportions of desirable practices regarding test request management, test tube labelling, test information search procedures, and the collection and handling of venous blood samples, but not regarding patient identification. Of the ward staff, only 5.5% had ever filed an error report regarding venous blood sampling, compared to 28% of the laboratory staff (Paper IV). In the experimental study (Paper V), no significant preanalytical effect of pneumatic tube transport was found for most haematology, coagulation and platelet function parameters. However, time-to-clot formation was significantly shorter (16%) in the pneumatic tube-transported samples, indicating an in vitro activation of global coagulation. Conclusions. The questionnaire study of the rated experiences of venous blood sampling ward staff is the first of its kind to survey manual tasks in the preanalytical phase. The results suggest a clinically important risk of preanalytical errors in the surveyed wards. Computerised test request management will eliminate some, but not all, of the identified risks. The better performance reported by the laboratory staff may reflect successful quality improvement initiatives in the laboratories. The current error reporting system needs to be functionally implemented. The experimental study indicates that pneumatic tube transport does not introduce preanalytical errors for regular tests, but manual transport is recommended for analysis with thromboelastographic technique. This thesis underscores the importance of quality improvement in the preanalytical phase of venous blood testing in hospitals.
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