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- Clarke, Robert, et al.
(författare)
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Lowering blood homocysteine with folic acid based supplements : Meta-analysis of randomised trials
- 1998
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Ingår i: British Medical Journal. - : BMJ. - 0959-8146. ; 316:7135, s. 894-898
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Forskningsöversikt (refereegranskat)abstract
- Objective: To determine the size of reduction in homocysteine concentrations produced by dietary supplementation with folic acid and with vitamins B-12 or B-6. Design: Meta-analysis of randomised controlled trials that assessed the effects of folic acid based supplements on blood homocysteine concentration. Multivariate regression analysis was used to determine the effects on homocysteine concentrations of different doses of folic acid and of the addition of vitamin B-12 or B-6. Subjects: Individual data on 1114 people included in 12 trials. Findings: The proportional and absolute reductions in blood homocysteine produced by folic acid supplements were greater at higher pretreatment blood homocysteine concentrations (P < 0.001) and at lower pretreatment blood folate concentrations (P < 0.001). After standardisation to pretreatment blood concentrations of homocysteine of 12 μmol/l and of folate of 12 nmol/l (approximate average concentrations for Western populations), dietary folic acid reduced blood homocysteine concentrations by 25% (95% confidence interval 23% to 28%; P < 0.001), with similar effects in the range of 0.5-5 mg folic acid daily. Vitamin B-12 (mean 0.5 mg daily) produced an additional 7% (3% to 10%) reduction in blood homocysteine. Vitamin B-6 (mean 16.5 mg daily) did not have a significant additional effect. Conclusions: Typically in Western populations, daily supplementation with both 0.5-5 mg folic acid and about 0.5 mg vitamin B-12 would be expected to reduce blood homocysteine concentrations by about a quarter to a third (for example, from about 12 μmol/l to 8-9 μmol/l). Large scale randomised trials of such regimens in high risk populations are now needed to determine whether lowering blood homocysteine concentrations reduces the risk of vascular disease.
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| 2. |
- Adami, Johanna, et al.
(författare)
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Evidence of an association between non-Hodgkin´s lymphoma and skin cancer
- 1995
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Ingår i: BMJ (Clinical research ed.). - : BMJ. - 0959-8138 .- 1468-5833. ; 310:6993, s. 1491-1495
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE--To investigate a possible link between exposure to ultraviolet light and the almost epidemic increase in non-Hodgkin's lymphoma worldwide. Because ultraviolet light is known to cause skin cancers, the association between non-Hodgkin's lymphoma and skin cancer was studied. DESIGN--Secondary occurrence of either malignant melanoma or squamous cell skin cancer in cohorts of patients with a first diagnosis of either non-Hodgkin's lymphoma or chronic lymphocytic leukaemia, and vice versa, were studied. Expected numbers of subsequent cancers were calculated by sex, age, and period specific national incidence rates multiplied by the person years under observation in the cohorts. SETTING--Denmark (1943-89) and Sweden (1958-89). SUBJECTS--Four population based cohorts identified in the nationwide cancer registries (34,641 people with non-Hodgkin's lymphoma, 17,400 with chronic lymphocytic leukaemia, 34,989 with malignant melanoma, 25,980 with squamous cell skin cancer). A total of 562,085 person years were accrued for the analysis. MAIN OUTCOME MEASURES--The ratios of observed to expected cancers (the standardised incidence ratio) served as a measure of the relative risk. RESULTS--The relative risk for developing squamous cell skin cancer was 5.5 (95% confidence interval 4.6 to 6.6) among patients with non-Hodgkin's lymphoma and 8.6 (7.2 to 10.3) among patients with chronic lymphocytic leukaemia. The relative risks remained high over more than 15 years of follow up. Relative risks for malignant melanoma were 2.4 (1.8 to 3.2) for patients with non-Hodgkin's lymphoma and 3.1 (2.1 to 4.4) for patients with chronic lymphocytic leukaemia. After squamous cell skin cancer had been diagnosed there was a twofold excess risk for non-Hodgkin's lymphoma and chronic lymphocytic leukaemia. By contrast, in each of the cohorts the general cancer risks excluding skin and lymphoproliferative malignancies were close to the expected. CONCLUSIONS--The occurrence of non-Hodgkin's lymphoma and skin cancer are strongly associated; this supports the hypothesis that the secular increase in exposure to ultraviolet light may have contributed to the increasing incidence of non-Hodgkin's lymphoma in recent decades.
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| 5. |
- Andersson, R, et al.
(författare)
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Fertility patterns after appendicectomy: historical cohort study
- 1999
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Ingår i: BRITISH MEDICAL JOURNAL. - : BRITISH MED JOURNAL PUBL GROUP. - 0959-8138. ; 318:7189, s. 963-967
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Tidskriftsartikel (refereegranskat)abstract
- Objective To examine fertility patterns in women who had their appendix removed in childhood. Design Historical cohort study with computerised data and fertility data for this cohort and for an age matched cohort of women from the Swedish general populati
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| 10. |
- Bergstrom, S, et al.
(författare)
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Health for all by the year 2000?
- 1996
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Ingår i: BMJ (Clinical research ed.). - : BMJ. - 0959-8138 .- 1468-5833. ; 313:7053, s. 316-316
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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