Upper limit of urea complex formation with n-heptane in the presence of n-1-heptene

1975 ◽  
Vol 11 (2) ◽  
pp. 97-98
Author(s):  
T. A. Volkova ◽  
I. D. Makhinya ◽  
A. I. Bogatova ◽  
V. A. Matishev
Keyword(s):  
Complex Formation ◽  
Urea Complex ◽  
Upper Limit

scholarly journals Macro-B12 masking B12 deficiency

2022 ◽  
Vol 15 (1) ◽  
pp. e247660
Author(s):  
Bruce H R Wolffenbuttel ◽  
Anneke C Muller Kobold ◽  
Agata Sobczyńska‐Malefora ◽  
Dominic J Harrington
Keyword(s):  
Clinical Practice ◽  
Complex Formation ◽  
Young Woman ◽  
Liver Diseases ◽  
Binding Proteins ◽  
Elevated Serum ◽  
Neurologic Symptoms ◽  
Upper Limit ◽  
Oral Form ◽  
B12 Deficiency

In clinical practice, the finding of an elevated serum B12 concentration is often the consequence of supplementation with B12 in either oral form or injections. Also, elevated serum B12 may be associated with underlying disorders, like liver diseases or a (haematologic) malignancy. Only a few studies have shown that it may also be the consequence of complex formation of B12-vitamin binding proteins with immunoglobulins, the so-called macro-B12. We describe a young woman who previously was diagnosed with B12 deficiency, and in whom, after cessation of B12 injection treatment, neurologic symptoms re-appeared, and despite this, repeatedly elevated serum B12 concentrations above the upper limit of the assay were found. We demonstrated that this was caused by the presence of macro-B12, which not only resulted in erroneous and longstanding elevated serum B12, but also masked her underlying B12 deficiency.

Correlation of Fatty Acid Structure With Preferential Order of Urea Complex Formation

1967 ◽  
Vol 50 (5) ◽  
pp. 1111-1118
Author(s):  
John L Iverson ◽  
R W Weik
Keyword(s):  
Fatty Acids ◽  
Fatty Acid ◽  
Complex Formation ◽  
Inclusion Compounds ◽  
Methyl Esters ◽  
Urea Complex ◽  
Fatty Acid Structure ◽  
Acid Structure

Abstract The selective order in which methyl esters of fatty acids form urea complexes was correlated with the fatty acid structure. Detailed information about the preferential order in which inclusion compounds are formed was obtained by fractionating complex oils (e.g., butter, lanolin, cod liver). The preferential order was correlated with GLC retention times, and the detection of trace amounts of fatty acids (<0.1%) was possible. Urea adductability values (UAV) are proposed as a useful means of expressing preferential order of the formation of inclusion compounds

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