Application of the Occupancy Principle in Studies of the Metabolism of Vitamin B12 in Man

1980 ◽  
Vol 58 (2) ◽  
pp. 169-171 ◽  
Author(s):  
R. G. Bessent ◽  
W. S. Watson ◽  
Caroline M. L. A. MacDonald ◽  
J. F. Adams
Keyword(s):  
Dietary Intake ◽  
Vitamin B12 ◽  
Body Mass ◽  
Pernicious Anaemia ◽  
Whole Body ◽  
Control Subjects

1. The long-term clearance of radioactive vitamin B12 from serum and from whole body was measured in control subjects and patients with treated pernicious anaemia and the data were analysed by the occupancy principle to provide estimates of dietary intake, daily requirements and whole-body mass of vitamin B12. 2. In six cases the daily requirement for vitamin B12 ranged from 0·15 to 1·9 μg with an average of 1·0 μg. The whole-body vitamin B12 in four cases ranged from 780 to 1350 μg with an average of 1060 μg. 3. Estimates of the whole-body vitamin B12 on the assumption of single-pool equilibrium gave constantly changing results, which, together with discrepant half-lives for serum radioactivity and whole-body radioactivity, constitute evidence against the concept of single-pool equilibrium.

Factors affecting the Absorption of Vitamin B12

1972 ◽  
Vol 43 (2) ◽  
pp. 233-250 ◽  
Author(s):  
J. F. Adams ◽  
D. J. Clow ◽  
Sheila K. Ross ◽  
K. Boddy ◽  
Priscilla King ◽  
...  
Keyword(s):  
Vitamin B12 ◽  
Intrinsic Factor ◽  
Pernicious Anaemia ◽  
Whole Body ◽  
Factors Affecting ◽  
Control Subjects ◽  
Tracer Techniques ◽  
Receptor Sites ◽  
Body Counting ◽  
Dose Levels

1. The absorption of radioactive cobalamin was measured by a whole-body counting technique in control subjects and in patients with pernicious anaemia. 2. The absorption of cyanocobalamin by patients with pernicious anaemia was decreased by charcoal but not by bile or saliva. 3. The absorption of cyanocobalamin by control subjects was not affected by food but was significantly increased by pentagastrin. With pentagastrin the absorption of cyanocobalamin was significantly greater than that of hydroxocobalamin. The hog intrinsic factor-mediated absorption of cyanocobalamin by patients with pernicious anaemia was significantly depressed by pentagastrin. 4. The effect of increasing the mass of hog intrinsic factor concentrate on the absorption of cyanocobalamin by patients with pernicious anaemia could be described by a function relating the amount absorbed, the mass of intrinsic factor and two constants. The relationship implies that when the mass of intrinsic factor is small the amount of cyanocobalamin absorbed is directly proportional to the mass of intrinsic factor but that absorption approaches a saturation value with increasing mass of intrinsic factor. In physiological terms the function implies that absorption is proportional to the amount of cyanocobalamin attached to receptor sites but that cyanocobalamin attached to receptor sites may become detached and either reattached or lost to absorption. 5. With oral doses of 25 μg and 50 μg, control subjects absorbed more cyanocobalamin and hydroxocobalamin than patients with pernicious anaemia. At both dose levels control subjects absorbed more cyanocobalamin than hydroxocobalamin but no difference was observed in patients with pernicious anaemia. The intrinsic factor mechanism therefore influences amounts absorbed at such dose levels and appears to be a factor in the differences in absorption of cyanocobalamin and hydroxocobalamin. 6. The use of double-tracer techniques makes it possible for each subject to act as his own control in studies of vitamin B12 absorption. The value of this technique is stressed.

Decreased Bone Density in Adolescent Girls With Anorexia Nervosa

PEDIATRICS ◽  
1990 ◽  
Vol 86 (3) ◽  
pp. 440-447 ◽  
Author(s):  
Laura K. Bachrach ◽  
David Guido ◽  
Debra Katzman ◽  
Iris F. Litt ◽  
Robert Marcus
Keyword(s):  
Bone Mineral Density ◽  
Body Mass Index ◽  
Anorexia Nervosa ◽  
Bone Density ◽  
Bone Mass ◽  
Body Mass ◽  
Bone Mineral ◽  
Whole Body ◽  
Mineral Density ◽  
Control Subjects

Osteoporosis develops in women with chronic anorexia nervosa. To determine whether bone mass is reduced in younger patients as well, bone density was studied in a group of adolescent patients with anorexia nervosa. With single- and dual-photon absorptiometry, a comparison was made of bone mineral density of midradius, lumbar spine, and whole body in 18 girls (12 to 20 years of age) with anorexia nervosa and 25 healthy control subjects of comparable age. Patients had significantly lower lumbar vertebral bone density than did control subjects (0.830 ± 0.140 vs 1.054 ± 0.139 g/cm2) and significantly lower whole body bone mass (0.700 ± 0.130 vs 0.955 ± 0.130 g/cm2). Midradius bone density was not significantly reduced. Of 18 patients, 12 had bone density greater than 2 standard deviations less than normal values for age. The diagnosis of anorexia nervosa had been made less than 1 year earlier for half of these girls. Body mass index correlated significantly with bone mass in girls who were not anorexic (P < .05, .005, and .0001 for lumbar, radius, and whole body, respectively). Bone mineral correlated significantly with body mass index in patients with anorexia nervosa as well. In addition, age at onset and duration of anorexia nervosa, but not calcium intake, activity level, or duration of amenorrhea correlated significantly with bone mineral density. It was concluded that important deficits of bone mass occur as a frequent and often early complication of anorexia nervosa in adolescence. Whole body is considerably more sensitive than midradius bone density as a measure of cortical bone loss in this illness. Low body mass index is an important predictor of this reduction in bone mass.

Long-Term Clearance of [57Co]Cyanocobalamin in Vegans and Pernicious Anaemia

1980 ◽  
Vol 58 (1) ◽  
pp. 101-103 ◽  
Author(s):  
S. Amin ◽  
T. Spinks ◽  
A. Ranicar ◽  
M. D. Short ◽  
A. V. Hoffbrand
Keyword(s):  
Intrinsic Factor ◽  
Pernicious Anaemia ◽  
Normal Subjects ◽  
Whole Body ◽  
Least Squares Fit ◽  
Significant Difference ◽  
Maximum Period ◽  
Body Counting ◽  
Whole Body Counting

1. Whole-body counting has been used to monitor the clearance of [57Co]cyanocobalamin in normal subjects, vegans and patients with pernicious anaemia. After oral administration of 57Colabelled cyanocobalamin (1 μg/l μCi), subjects were counted for radioactivity monthly for a maximum period of 1 year. 2. The results obtained were consistent with a monoexponential clearance model and a least-squares fit showed that there was no significant difference between the mean clearance rates for the vegans and normal subjects. 3. The patients with pernicious anaemia cleared the vitamin significantly more quickly than the normal control subjects. 4. This may be due to failure to reabsorb biliary vitamin B12 in pernicious anaemia because of the absence of intrinsic factor.

Evidence of Altered Copper Metabolism in Patients with Chronic Pancreatitis

1981 ◽  
Vol 60 (3) ◽  
pp. 303-310 ◽  
Author(s):  
Joan M. Braganza ◽  
H. J. Klass ◽  
M. Bell ◽  
G. Sturniolo
Keyword(s):  
Chronic Pancreatitis ◽  
Intravenous Injection ◽  
Copper Content ◽  
Copper Metabolism ◽  
Bladder Function ◽  
Whole Body ◽  
Duodenal Juice ◽  
Copper Absorption ◽  
Control Subjects

1. The copper content of duodenal juice obtained during secretin-pancreozymin tests has been compared in 12 healthy volunteers and 12 patients with chronic pancreatitis in whom normal gall-bladder function was confirmed by oral cholecystography. Of the 12 chronic pancreatitis patients 10 had not received any pancreatic supplement, one was on supplements for 10 years and one for 2 years. 2. In the control subjects the output of copper secretion into the duodenum displayed two phases: a sharp increase in the first 10 min after secretin [intravenous injection of 2 Crick-Harper-Raper units/kg of secretin (Boots)] and a second sharp rise in the first 10 min after pancreozymin [intravenous injection of 2 Crick-Harper-Raper units/kg of pancreozymin (Boots)]. 3. In patients with chronic pancreatitis the pattern of copper secretion was similar to that of control subjects, but in the first 10 min after secretin the output of copper was significantly higher (P < 0.001). The post-secretin output of bilirubin was also higher in chronic pancreatitis (P < 0.02), but the volume of duodenal juice (P < 0.01), the outputs of bicarbonate (P < 0.001) and trypsin (0.05 < P < 0.1) were reduced compared with those of control subjects. The parallel increases in outputs of bilirubin and copper suggested that bile was the source of the increased copper in this group. 4. In the two chronic pancreatitis patients who received pancreatic supplements the post-secretin copper outputs were within normal limits. In a further group of five chronic pancreatitis patients who had been taking pancreatic supplements for many years the post-secretin copper output was not only less than in untreated chronic pancreatitis patients (P < 0.001), but less than in control subjects (P < 0.005). The output of bilirubin was similarly reduced (P < 0.01 and < 0.02 respectively). 5. Since bile is the major route for disposal of absorbed copper and since, under normal steady-state conditions, biliary copper excretion provides an index of copper absorption, our data suggest differences in long-term copper absorption between untreated and treated chronic pancreatitis patients. A component in pancreatic juice may therefore limit copper absorption under normal circumstances. Untreated chronic pancreatitis patients (who lack this factor) would absorb more copper, producing, over many years, an increase in hepatic and whole-body copper content. Long-term feeding of pancreatic supplements, by reducing copper absorption, would gradually deplete whole-body copper content.

scholarly journals Long-term Trial of Oral Treatment of Pernicious Anaemia with Vitamin-B12-Peptide

BMJ ◽  
1963 ◽  
Vol 1 (5345) ◽  
pp. 1583-1585 ◽  
Author(s):  
J. L. Withey ◽  
J. H. Jones ◽  
G. S. Kilpatrick
Keyword(s):  
Vitamin B12 ◽  
Oral Treatment ◽  
Pernicious Anaemia ◽  
Term Trial

LONG-TERM TRIAL OF ORAL VITAMIN B12 IN PERNICIOUS ANÆMIA

The Lancet ◽  
1962 ◽  
Vol 280 (7256) ◽  
pp. 577-579 ◽  
Author(s):  
R.B. Thompson ◽  
D.W. Ashby ◽  
Edna Armstrong
Keyword(s):  
Vitamin B12 ◽  
Pernicious Anaemia ◽  
Oral Vitamin ◽  
Term Trial

Long term dietary intake of aromatic amino acids are associated with leptin gene expression in adipose tissues of non-diabetic adults

2018 ◽  
Author(s):  
Golaleh Asghari ◽  
Emad Yuzbashian ◽  
Maryam Zarkesh ◽  
Parvin Mirmiran ◽  
Mehdi Hedayati ◽  
...  
Keyword(s):  
Gene Expression ◽  
Amino Acids ◽  
Dietary Intake ◽  
Aromatic Amino Acids ◽  
Adipose Tissues
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