共查询到20条相似文献,搜索用时 31 毫秒
1.
D. Glenn Kennedy W. John Blanchflower Paul B. Young W. Brian Davidson 《Biological trace element research》1992,35(2):153-166
The first development of an α-face-specific radioimmunoassay for vitamin B12 is described. Sheep, fed a cobalt-deficient diet, and immunized with a conjugate between Co-β carboxypropyl cobalamin and
keyhole limpet hemocyanin, were used to produce antisera. The antisera crossreacted with Co-β derivatives of vitamin B12, but did not crossreact with the α-face vitamin B12 analog cobinamide. The antisera were used to develop a sensitive and reproducible radioimmunoassay that was free from contamination
with the nonspecific vitamin B12 binding protein, R-protein. Both the radioimmunoassay and measurements of plasma concentrations of methylmalonic acid were
applied to the diagnosis of cobalt/vitamin B12 deficiency in sheep. The assay correlated well with a commercially available radioassay and did not falsely detect normal
vitamin B12 concentration in plasma samples containing elevated concentrations of methylmalonic acid. 相似文献
2.
Macrogranulocytic and/or erythroid megaloblastic bone marrow changes which could not be accurately predicted from the hematologic findings in the blood were present in 25% of 305 mildly to moderately anemic pregnant women attending a public antepartum clinic in Montreal. Iron deficiency was the primary cause of anemia in most instances. Serum folate activity of less than 4.1 ng./ml. and/or serum vitamin B12 levels of less than 100 pg./ml. were present in 90% of the 77 patients having these bone marrow changes, whereas approximately one-third of 228 patients with normoblastic marrow had these low values. Red cell folate did not correlate as well as serum folate activity with bone marrow changes. After treatment with oral folic acid in the range of 0.2 mg. to 0.8 mg., daily, for seven to 14 days, the megaloblastic and macrogranulocytic changes in patients with low serum folate activity and normal serum vitamin B12 values disappeared in 15 of 21 patients. Of five women having both low folate and vitamin B12 values, three failed to respond and two showed only partial improvement after 0.4 mg. of folic acid daily, per os, for 10 days. The average diet of these anemic women was suboptimal in folate and in iron. 相似文献
3.
The classic neurological and psychiatric features associated with vitamin B12 deficiency have been well described and are the subject of many excellent review articles. The advent of sensitive diagnostic tests, including homocysteine and methylmalonic acid assays, has revealed a surprisingly high prevalence of a more subtle ‘subclinical’ form of B12 deficiency, particularly within the elderly. This is often associated with cognitive impairment and dementia, including Alzheimer's disease. Metabolic evidence of B12 deficiency is also reported in association with other neurodegenerative disorders including vascular dementia, Parkinson's disease and multiple sclerosis. These conditions are all associated with chronic neuro-inflammation and oxidative stress. It is possible that these clinical associations reflect compromised vitamin B12 metabolism due to such stress. Physicians are also increasingly aware of considerable inter-individual variation in the clinical response to B12 replacement therapy. Further research is needed to determine to what extent this is attributable to genetic determinants of vitamin B12 absorption, distribution and cellular uptake. 相似文献
4.
P. D. Roberts Helen James Aviva Petrie J. O. Morgan A. V. Hoffbrand 《BMJ (Clinical research ed.)》1973,3(5871):67-72
Haemoglobin, serum vitamin B12, and serum and red cell folate levels have been measured in 322 pregnant immigrant women in London at their first booking and in a proportion at 34 weeks of gestation and postnatally. The Indian, East-African Indian, and Pakistani and Bangladeshi patients showed significantly lower initial mean serum vitamin B12 levels than the European group, the levels being lower in Hindu and Sikh patients than in Moslems. The patients of West Indian, Indian, and East-African Indian origin showed significantly lower initial mean haemoglobin levels than the immigrants from European countries. Though there was no overall correlation between haemoglobin and serum vitamin B12 level the incidence of hypersegmented polymorphs and macrocytosis in the peripheral blood was highest in the Indian and East-African Indian patients, and both these features were particularly frequent in patients with subnormal serum vitamin B12 levels. Only one patient, however, had overt megaloblastic anaemia due to vitamin B12 deficiency. The Indian patients whose red cell folate levels were less than 200 ng/ml also had a lower mean serum vitamin B12 level than those with red cell folate levels greater than 200 ng/ml. The Indian patients had smaller babies than the Europeans but this was not related to the differences in vitamin B12 status between the two groups. However, out of 39 babies of the Indian group 5 (13%) showed subnormal serum vitamin B12 levels in the first 10 days of life, the lowest level being 120 pg/ml.Though there was an overall statistically significant fall in serum vitamin B12 between first booking and 34 weeks of pregnancy there was no significant fall in serum vitamin B12 in those who initially had subnormal levels. Thus many Indian women are vitamin B12 deficient in pregnancy, and this is associated with morphological blood abnormalities in many cases, but megaloblastic anaemia due to this deficiency is relatively infrequent. 相似文献
5.
J. F. Adams 《BMJ (Clinical research ed.)》1970,1(5689):138
The relation between the serum vitamin B12 level and the daily loss of vitamin B12 in urine was examined in patients with normal serum vitamin B12 levels and in patients suffering from vitamin B12 deficiency. A linear correlation was found between the two measurements, suggesting that the serum vitamin B12 level is a governing factor in the urinary loss of vitamin B12. The contribution by this loss to the total loss of vitamin B12 from the body is small under normal circumstances but becomes quantitatively more important with the depletion of body stores. 相似文献
6.
Generalized skin pigmentation in five African women with megaloblastic anaemia in the postnatal period was associated with low serum folate levels, as distinct from vitamin B12 deficiency. It is suggested that the occurrence of pigmentation in both folate and vitamin B12 deficiency may reflect a common abnormality of metabolism. 相似文献
7.
《Archives of animal nutrition》2013,67(2):162-168
Vitamin B12-deficiency may induce specific symptoms as neurological alterations and unspecific symptoms such as anaemia and growth retardation. In this study, maternal vitamin B12 deficiency from end of gestation to weaning was evaluated in mouse dams, which was provoked by feeding a vitamin B12-deficient diet. The animals were divided into two groups (control and deficient). The control group received the vitamin B12-deficient diet supplemented with commercial vitamin B12. Compared to the control, the vitamin B12-deficient dams and their offspring showed a significant decrease of body weight (by 20 and 39%, respectively), serum vitamin B12 concentration (by 61 and 67%, respectively), haematological values as haematocrit (25 and 26%, respectively), and IgA producer cells (by 36 and 54%, respectively). In both, vitamin B12-deficient mouse dams and their offspring, histological alterations of small intestine were observed, whereas growth retardation occurred in the offspring only. This experimental murine model allows assessing the incidence of maternal cobalamin deficiency in offspring and would be useful for evaluating novel adjuncts such as functional foods to prevent vitamin B12 deficiency. 相似文献
8.
Imerslund-Gräsbeck syndrome (IGS) or selective vitamin B12 (cobalamin) malabsorption with proteinuria is a rare autosomal recessive disorder characterized by vitamin B12 deficiency commonly resulting in megaloblastic anemia, which is responsive to parenteral vitamin B12 therapy and appears in childhood. Other manifestations include failure to thrive and grow, infections and neurological damage. Mild proteinuria (with no signs of kidney disease) is present in about half of the patients. Anatomical anomalies in the urinary tract were observed in some Norwegian patients. Vitamin B12 absorption tests show low absorption, not corrected by administration of intrinsic factor. The symptoms appear from 4 months (not immediately after birth as in transcobalamin deficiency) up to several years after birth. The syndrome was first described in Finland and Norway where the prevalence is about 1:200,000. The cause is a defect in the receptor of the vitamin B12-intrinsic factor complex of the ileal enterocyte. In most cases, the molecular basis of the selective malabsorption and proteinuria involves a mutation in one of two genes, cubilin (CUBN) on chromosome 10 or amnionless (AMN) on chromosome 14. Both proteins are components of the intestinal receptor for the vitamin B12-intrinsic factor complex and the receptor mediating the tubular reabsorption of protein from the primary urine. Management includes life-long vitamin B12 injections, and with this regimen, the patients stay healthy for decades. However, the proteinuria persists. In diagnosing this disease, it is important to be aware that cobalamin deficiency affects enterocyte function; therefore, all tests suggesting general and cobalamin malabsorption should be repeated after abolishment of the deficiency. 相似文献
9.
《Endocrine practice》2010,16(2):205-208
ObjectiveTo estimate the frequency of undiagnosed vitamin B12 deficiency among patients with type 2 diabetes mellitus who had not taken metformin during at least the prior 5 years and to ascertain whether vitamin B12 deficiency among the patients with type 2 diabetes was due to nutritional deficiency or malabsorption.MethodsSerum vitamin B12 levels were measured in 44 subjects with diabetes and a mean age of 51 years (range, 40 to 70), 21 (48%) of whom had low levels (< 200 pg/mL). Of those 21 patients, 10 agreed to enroll in an intervention phase consisting of oral supplementation with mecobalamin, 1,500 μg daily for 3 months. Those patients in whom vitamin B12 levels failed to normalize after oral supplementation alone would be presumed to have vitamin B12 deficiency attributable to malabsorption.ResultsAlmost half of the subjects with type 2 diabetes not taking metformin had biochemically proven vitamin B12 deficiency. All 10 subjects who enrolled in the intervention phase had normalization of their vitamin B12 levels after 3 months of oral supplementation with mecobalamin.ConclusionWe conclude that vitamin B12 deficiency is common among patients with type 2 diabetes and was related to nutrition in our study group. In addition to intensive glycemic control, vitamin B12 supplementation should be considered for treatment of diabetic neuropathy. In almost 50% of patients with low vitamin B12 levels, the deficiency was corrected with oral supplementation only. This, indeed, is an important finding, inasmuch as oralvitamin B12 supplementation is easy, convenient, and readily accepted by patients. This finding highlights the need for aggressive and early diagnosis and treatment to avoid complications of vitamin B12 deficiency. (Endocr Pract. 2010;16:205-208) 相似文献
10.
Honor M. Kidd 《CMAJ》1965,92(6):261-263
From 25 patients with acute leukemia 116 specimens of leukocytes were assayed microbiologically for total vitamin B12 to determine if variation in vitamin B12 content would help in differentiating the acute leukemias. The mean cell vitamin B12 levels (μμg./108 cells) in the different types of leukemia were: lymphoblastic 464, myeloblastic 1058 and monocytic 200. Cell vitamin B12 levels above the normal range (100-800 μμg./108 cells) are suggestive of myeloblastic leukemia. The only elevated cell vitamin B12 levels comparable to those found in myeloblastic leukemia were in reticulum cell leukemia, and this type of leukemia was not difficult to diagnose morphologically. Blast cells contained more vitamin B12 than mature cells of the same series; there was a significant positive correlation between the percentage of blast cells and cell levels of total vitamin B12 in both lymphoblastic and myeloblastic leukemia. 相似文献
11.
The development and role of international biological reference materials in the diagnosis of anaemia
Susan J. Thorpe 《Biologicals》2010,38(4):449-458
Anaemia is a major global health problem. Although the main cause is iron deficiency, anaemia also results from other nutritional deficiencies (folate and vitamin B12), haemolytic disorders including haemoglobinopathies, and bone marrow disorders. Accurate diagnosis of anaemia is dependent on reliable diagnostic tests and reference ranges, which in turn are dependent on effective standardisation. Standardisation is achieved through the availability of reference materials and reference measurement procedures. International biological reference materials have therefore been developed to standardise and control diagnostic tests for anaemia for a diverse range of analytes including total haemoglobin and haemoglobin types, ferritin, the serum transferrin receptor, serum vitamin B12 and folate, whole blood folate, and alloantibodies which mediate immune haemolytic anaemia. 相似文献
12.
Free and total vitamin B12 levels in serum and cerebrospinal fluid (CSF) were bioassayed, since there were no available data on the relationship between free and total vitamin B12 in CSF or between free vitamin in serum and CSF vitamin B12. The subjects were 43 neurological patients. Serum levels were normal in 40 of 43 patients. Values for free and total vitamin B12 in CSF were the same in 42 of 43 patients. Mean CSF vitamin B12 was 21 μμg./ml. In 17 cases CSF vitamin B12 equalled free vitamin B12 level in serum, in 16 cases CSF vitamin B12 was lower than the free level in serum, and in 10 cases CSF vitamin B12 was higher than the free vitamin level in serum. There was no apparent diagnostic correlation. The findings suggest that vitamin B12 is not bound in CSF and that there is some selective control of passage of vitamin B12 across the blood-CSF barrier. 相似文献
13.
Katsumi Shibata Chifumi Nakata Tsutomu Fukuwatari 《Bioscience, biotechnology, and biochemistry》2016,80(2):304-312
B-group vitamins are involved in the catabolism of 2-oxo acids. To identify the functional biomarkers of B-group vitamins, we developed a high-performance liquid chromatographic method for profiling 2-oxo acids in urine and applied this method to urine samples from rats deficient in vitamins B1 and B6 and pantothenic acid. 2-Oxo acids were reacted with 1,2-diamino-4,5-methylenebenzene to produce fluorescent derivatives, which were then separated using a TSKgel ODS-80Ts column with 30 mmol/L of KH2PO4 (pH 3.0):acetonitrile (7:3) at a flow rate of 1.0 mL/min. Vitamin B1 deficiency increased urinary levels of all 2-oxo acids, while vitamin B6 deficiency only increased levels of sum of 2-oxaloacetic acid and pyruvic acid, and pantothenic acid deficiency only increased levels of 2-oxoisovaleric acid. Profiles of 2-oxo acids in urine samples might be a non-invasive way of clarifying the functional biomarker of B-group vitamins. 相似文献
14.
PARRY has speculated that in megaloblastic anaemia, deficiency of folate or vitamin B12 may mean that a population of cells is formed in the marrow containing DNA with subnormal amounts of thymidine, so accounting for some of the abnormalities of megaloblastic erythropoiesis1. We have therefore determined the base composition of DNA from normal and megaloblastic cells and have also measured the amounts of 5-methylcytosine2,3 present in these DNA preparations, as vitamin B12 and folate are known to be concerned in many methylation reactions in man4 and could be directly or indirectly concerned in the formation of 5-methylcytosine. 相似文献
15.
Julie Robertson Francesco Iemolo Sally P. Stabler Robert H. Allen J. David Spence 《CMAJ》2005,172(12):1569-1573
Background
Carotid plaque area is a strong predictor of cardiovascular events. High homocysteine levels, which are associated with plaque formation, can result from inadequate intake of folate and vitamin B12. Now that folic acid fortification is widespread in North America, vitamin B12 has become an important determinant of homocysteine levels. We sought to determine the prevalence of low serum levels of vitamin B12, and their relation to homocysteine levels and carotid plaque area among patients referred for treatment of vascular disease since folic acid fortification of enriched grain products.Methods
We evaluated 421 consecutive new patients with complete data whom we saw in our vascular disease prevention clinics between January 1998 and January 2002. We measured total carotid plaque area by ultrasound and determined homocysteine and serum vitamin B12 levels in all patients.Results
The patients, 215 men and 206 women, ranged in age from 37 to 90 years (mean 66 years). Most were taking medications for hypertension (67%) and dyslipidemia (62%). Seventy-three patients (17%) had vitamin B12 deficiency (vitamin B12 level < 258 pmol/L with homocysteine level > 14 μmol/L or methylmalonic acid level > 271 nmol/L). The mean area of carotid plaque was significantly larger among the group of patients whose vitamin B12 level was below the median of 253 pmol/L than among those whose vitamin B12 level was above the median: 1.36 (standard deviation [SD] 1.27) cm2 v. 1.09 (SD 1.0) cm2; p = 0.016.Conclusions
Vitamin B12 deficiency is surprisingly common among patients with vascular disease, and, in the setting of folic acid fortification, low serum vitamin B12 levels are a major determinant of elevated homocysteine levels and increased carotid plaque area.Elevated plasma total homocysteine levels are a strong, graded independent risk factor for stroke and myocardial infarction.1,2 Mechanisms by which homocysteine may cause vascular disease include a propensity for thrombosis and impaired thrombolysis, increased production of hydrogen peroxide, endothelial dysfunction and increased oxidation of low-density lipoproteins and Lp(a) lipoproteins.3 Folic acid fortification of enriched cereal grain products began in North America in March 1996 and was made mandatory in 1998. Fortification has reduced the number of neural tube defects by half,4 which is clearly a beneficial outcome, but so far it has had little impact on cardiovascular mortality.5Carotid plaque area is a strong predictor of cardiovascular events.6 High homocysteine levels, which are associated with plaque formation, can result from inadequate intake of folate and vitamin B12. Now that folic acid fortification is widespread, vitamin B12 has become an important determinant of homocysteine levels.7 We sought to determine the prevalence of low serum levels of vitamin B12, and their relation to homocysteine levels and carotid plaque area among patients referred for treatment of vascular disease since folic acid fortification of enriched grain products. 相似文献16.
J.B. Ubbink W.J.H. Vermaak S.H. Bissbort 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》1991,566(2)
Human lymphocyte kynureninase activity was assessed in homogenized cells by determination of 3-hydroxyanthranilic acid production as a function of time after addition of the substrate, 3-hydroxykynurenine. The product, 3-hydroxyanthranilic acid, was determined by isocratic high-performance liquid chromatography and fluorescence detection. Mean (± S.D.) lymphocyte kynureninase activity in a group (n = 12) of vitamin B6-deficient men was 5.04 ± 0.81 pmol 3-hydroxyanthranilic acid formed per mg protein per min, which was significantly (p=0.005) lower than the 6.69 ± 1.70 pmol 3-hydroxyanthranilic acid formed per mg protein per min in men with a normal vitamin B6 status. This indicates that lymphocyte kynureninase activity is depressed during a vitamin B6 deficiency. 相似文献
17.
Two siblings with megaloblastic anemia responsive to parenteral vitamin B12 were studied to elucidate the cause of the B12 deficiency. Gastric juice from both contained acid and functional intrinsic factor. Serum contained transcobalamin II and lacked antibodies to intrinsic factor. Schilling tests showed vitamin B12 malabsorption uncorrected by hog intrinsic factor or pancreatic extract. Other parameters of small intestinal function were normal. Proteinuria was initially present in both but cleared in one following treatment with B12. These patients with “familial selective vitamin B12 malabsorption” are the first reported from Canada. Only 37 cases have been reported in the world literature to date. 相似文献
18.
Donghoon Kang Jae-Seung Yun Sun-Hye Ko Tae-Seok Lim Yu-Bae Ahn Yong-Moon Park Seung-Hyun Ko 《PloS one》2014,9(10)
Long-term and high-dose treatment with metformin is known to be associated with vitamin B12 deficiency in patients with type 2 diabetes. We investigated whether the prevalence of B12 deficiency was different in patients treated with different combination of hypoglycemic agents with metformin during the same time period. A total of 394 patients with type 2 diabetes treated with metformin and sulfonylurea (S+M group, n = 299) or metformin and insulin (I+M group, n = 95) were consecutively recruited. The vitamin B12 and folate levels were quantified using the chemiluminescent enzyme immunoassay. Vitamin B12 deficiency was defined as vitamin B12≤300 pg/mL without folate deficiency (folate>4 ng/mL). The mean age of and duration of diabetes in the subjects were 59.4±10.5 years and 12.2±6.7 years, respectively. The mean vitamin B12 level of the total population was 638.0±279.6 pg/mL. The mean serum B12 levels were significantly lower in the S+M group compared with the I+M group (600.0±266.5 vs. 757.7±287.6 pg/mL, P<0.001). The prevalence of vitamin B12 deficiency in the metformin-treated patients was significantly higher in the S+M group compared with the I+M group (17.4% vs. 4.2%, P = 0.001). After adjustment for various factors, such as age, sex, diabetic duration, duration or daily dose of metformin, diabetic complications, and presence of anemia, sulfonylurea use was a significant independent risk factor for B12 deficiency (OR = 4.74, 95% CI 1.41–15.99, P = 0.012). In conclusion, our study demonstrated that patients with type 2 diabetes who were treated with metformin combined with sulfonylurea require clinical attention for vitamin B12 deficiency and regular monitoring of their vitamin B12 levels. 相似文献
19.
《Animal : an international journal of animal bioscience》2019,13(4):750-759
Vitamin B12 is synthesised in the rumen from cobalt (Co) and has a major role in metabolism in the peri-paturient period, although few studies have evaluated the effect of the dietary inclusion of Co, vitamin B12 or injecting vitamin B12 on the metabolism, health and performance of high yielding dairy cows. A total of 56 Holstein-Friesian dairy cows received one of four treatments from 8 weeks before calving to 8 weeks post-calving: C, no added Co; DC, additional 0.2 mg Co/kg dry matter (DM); DB, additional 0.68 mg vitamin B12/kg DM; IB, intra-muscular injection of vitamin B12 to supply 0.71 mg/cow per day prepartum and 1.42 mg/cow per day post-partum. The basal and lactation rations both contained 0.21 mg Co/kg DM. Cows were weighed and condition scored at drying off, 4 weeks before calving, within 24 h of calving and at 2, 4 and 8 weeks post-calving, with blood samples collected at drying off, 2 weeks pre-calving, calving and 2, 4 and 8 weeks post-calving. Liver biopsy samples were collected from all animals at drying off and 4 weeks post-calving. Live weight changed with time, but there was no effect of treatment (P>0.05), whereas cows receiving IB had the lowest mean body condition score and DB the highest (P<0.05). There was no effect of treatment on post-partum DM intake, milk yield or milk fat concentration (P>0.05) with mean values of 21.6 kg/day, 39.6 kg/day and 40.4 g/kg, respectively. Cows receiving IB had a higher plasma vitamin B12 concentration than those receiving any of the other treatments (P<0.001), but there was no effect (P>0.05) of treatment on homocysteine or succinate concentrations, although mean plasma methylmalonic acid concentrations were lower (P=0.019) for cows receiving IB than for Control cows. Plasma β-hydroxybutyrate concentrations increased sharply at calving followed by a decline, but there was no effect of treatment. Similarly, there was no effect (P>0.05) of treatment on plasma non-esterified fatty acids or glucose. Whole tract digestibility of DM and fibre measured at week 7 of lactation were similar between treatments, and there was little effect of treatment on the milk fatty acid profile except for C15:0, which was lower in cows receiving DC than IB (P<0.05). It is concluded that a basal dietary concentration of 0.21 mg Co/kg DM is sufficient to meet the requirements of high yielding dairy cows during the transition period, and there is little benefit from additional Co or vitamin B12. 相似文献
20.
The excretion in the urine of 58Co after an oral dose of 58Co vitamin B12 given together with intrinsic factor has been found to be reduced in a number of patients with psoriasis, eczema, and other less common dermatoses. There is a correlation between the abnormality and the extent of the rash. A reduced glomerular filtration rate was found in a few of the patients in whom it was measured, and this must have been responsible, at least in part, for the reduced excretion of vitamin B12 in these patients, but abnormal vitamin B12 excretion also occurred in the absence of impaired renal function. Our evidence is insufficient to show whether malabsorption or increased tissue utilization of vitamin B12 was the explanation in other cases. Certainly a number of patients had steatorrhoea, and in these it is most likely that malabsorption was the major factor. In patients without steatorrhoea a lone malabsorption of vitamin B12 cannot be excluded. A decreased serum concentration of vitamin B12 was found in only one of the patients. 相似文献