Biomedical subjects
Publications and source records attributed to D Labie.
Haemoglobin Belfast was initially observed in an Irish patient. The second case, found in a French patient suffering from a metastatic carcinoma, is here described. Both observations are compared from clinical, haematological and biochemical points of view. Functional and spectrophotometrical studies confirmed the slight abnormalities already described.
In Hemoglobins M, as the result of a mutation theheme iron of the abnormal chain is atabilized in an oxidized form unable to carry oxygen. In this paper, we discuss the case of hemoglobin M Boston characterizing this abnormal hemoglobin as valency hybrid by spectral studies and utilising this mutant as a marker, in isoelectricfocusing, we bring the arguments that the two intermediary bands of oxidation correspond to alpha2+beta2+2 and alpha2+2beta2+3 We also indicate that the abnormal spectrum of Hb M interferes with the estimation of methemoglobin, giving erroneous values. We have shown that isoelectric focusing and subsequent scanning give a definite idea about the amount of abnormal chain present.
Hemoglobin Casper (beta106Leu replaced by Pro) can be separated from hemoglobin (Hb) A by isoelectric focusing on polyacrylamide gel. This abnormal hemoglobin was estimated to be 30% of teh total by both isoelectric focusing and heat lability kinetics. Its oxygen equilibrium curves indicate a high oxygen affinity, low degree of subunit interaction, and a decreased Bohr effect. Mixtures of Hb Casper and Hb A appear to bind oxygen as if no hybrid molecules exist.
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Hemoglobin Cochin Port-Royal beta 146 (HC3) His yields Arg is the second example in which the beta C-terminal residue is replaced. Owing to the known importance of His beta 146 in the co-operative effects of hemoglobin, the functional properties of this variant were carefully studied. It had a normal Hill coefficient but a reduced alkaline Bohr effect. However, the reduction in Bohr effect is less than the halving predicted from previous mutants and modified hemoglobins.
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Hemoglobin chain synthesis during leukemic processes has been studied on patients having fetal hemoglobin. All cases showed the following abnormalities : (1) a relatively increased synthesis of the beta chain ; (2) an important increase of the free dimeric precursors pool, with, most of the time, a predominance of alpha chain. If the first point suggests an alpha-thalassemia feature, the presence of free alpha chains shows evidence for a more complex mechanism not only due to a decrease of messenger RNA. The hypothesis of a clonal disorder could neither be demonstrated nor ruled out. The observed abnormalities could be due to a defect in a alpha chain depending regulation mechanism.
A new case of haemoglobin Bucuresti beta 42 (CD1) Phe yields Leu is described in a Cuban family. The functional studies confirm the results already described--a low oxygen affinity and a decreased haem-haem interaction. In addition to this, the reactivity for 2, 3 diphosphoglycerate (2, 3 DPG) was shown to be normal. The instability is mostly due to a fast rate of haemichromes formation.
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The molecular evolution is considered in several protein families. It can be studied with the data of an entirely known structure, like in hemoglobin or cytochrome, or of only partial structural data, as for proteases or immunoglobulins. In the case of isozymes the study of physico-chemical and kinetic properties is more indirect. Finally, it is shown that the molecular mechanisms are always the same, happening probably at the same frequency, the differences being due to a variable selection by molecular constraints and adaptation to the environment.
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