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Alpha-hemoglobin stabilizing protein (AHSP), described as a chaperone of alpha-hemoglobin (α-Hb), is synthesized at a high concentration in the erythroid precursors. AHSP specifically recognizes the G and H helices of α-Hb and forms a stable complex with free α-Hb until its association with the partner β-subunits. Unlike the free β-Hb which are soluble and form homologous tetramers, freshly synthesized α-Hb chains are highly unstable molecular species which precipitate and generate reactive oxygen species within the erythrocyte precursors of the bone marrow leading to apoptosis and ineffective erythropoiesis. AHSP protects the free α-Hb chains in maintaining it in the soluble state. In this review, we report data from the literature and our laboratory concerning the key role of AHSP in the biosynthesis of Hb and its possible involvement in some disorders of the red blood cell as well as the hemoglobinopathies and we discuss its use as a prognostic tool in thalassemia syndromes., (Copyright © 2015 Elsevier Masson SAS. All rights reserved.)

Human utilization of recombinant proteins of therapeutical interest, as hemoglobin, implies that the transgenic host allows a low cost production of the active proteins with minimal risks of pathogen contamination. In this regard, the use of transgenic plants could be of great interest. In particular, the systems based on plants could be one of the most economical transgenic system, compared with the others, because biomass obtention in fields is not expensive.

Bovine hemoglobin (Hb) has been proposed as a potential blood substitute because of its low intrinsic oxygen affinity in the absence of chloride anions and 2,3-diphosphoglycerate. The use of bovine blood as a source of Hb does not eliminate the risks of viral infections. Biotechnology techniques allow to produce modified recombinant Hbs. We have engineered human Hb mutants with the aim of mimicking the functional properties of bovine Hb. The argument for this work resides in the crystallographic studies and in the comparison of human and bovine beta globin sequences. The mutant recombinant Hbs exhibit the heterotropic effects of bovine Hb do not exhibit the low intrinsic oxygen affinity of bovine Hb.

The search for a safe alternative to conventional blood transfusion has been directed towards either the use of synthetic perfluorochemicals or the biochemical manipulation of highly purified stroma-free Hb solutions prepared from outdated bank blood. However when using human blood, one does not eliminate the risks of viral infections. A novel source of Hb appeared with recent biotechnology techniques enabling one to synthesize recombinant Hb from microorganisms (E coli or S. cerevisiae) whose genome has been modified to contain globin genes. Normal human Hb A in solution, i.e. outside the red cells, is not suited for direct usage as a blood substitute because i) its high oxygen affinity, due to the absence of 2,3 DPG in the plasma, precludes sufficient O2 unloading to the tissues; ii) at low concentration, relative to that in the red cells, tetrameric Hb dissociates into dimers which escape the circulatory system by renal filtration or rapidly oxidize to the non functional metHb form. Expression of alpha- and beta-globins in Escherichia coli and in Saccharomyces cerevisiae enables one to introduce appropriate mutation(s) in the globin genes resulting in the expression of a synthetic Hb with low oxygen affinity, resembling that of normal whole blood; functional Hb has also been produced in a soluble form either in E. coli or in yeast. The coexpression of beta globin chains and alpha globin subunits linked by a peptide bond results in the direct synthesis of stabilized and fully functional Hb tetramers. Lastly, dilute haemoglobin solutions are prone to autooxidize and the rate of oxidation appears to be inversely proportional with the oxygen affinity of the heme groups.(ABSTRACT TRUNCATED AT 250 WORDS)

The well recognized prevalence of infectious agents in products derived from human whole blood and the increasing number of transfusion-transmitted diseases has made urgent the search for a safe alternative to conventional blood transfusion. Sources of hemoglobin (Hb) different from outdated human bank blood are under active scrutiny in several laboratories. Different approaches have been proposed to produce recombinant human Hb in bacteria (E. coli), yeast (S. cerevisiae) and transgenic mammals. These efforts have lead to the synthesis of recombinant human Hb with functional properties similar to those of native human Hb A. Site directed mutagenesis enables one to modify the structure of the recombinant globin chains with the view of lowering the oxygen affinity and increasing the stability of the tetramers. Progress is still necessary to ensure scaling-up and safe purification procedures, and to prolong shelf life of these solutions.

A further case of sporadic congenital sideroblastic anaemia is reported. Despite no contributing factors such as blood transfusion, oral ingestion of iron or alcoholic beverages, were present excessive iron stores occurred with consecutive tissue damage resulting in cirrhosis of the liver, portal hypertension and diabetes mellitus. HLA phenotype was A3 B7 as in primary hemochromatosis. Correction of anemia was obtained by vitamin B6 administration. Improvement of iron overload was achieved through the use of daily subcutaneous infusions of the iron chelating drug desferrioxamine with a portable infusion pump.

An iron rich tissue with an important pseudo-peroxidase activity and which specifically incorporates 55Fe and 3H delta aminolevulinic acid is localized around some vessels of the investigated Annelids : parapodial vessels of Nephthys, chloragogen coeca of Arenicola. This tissue which can be considered as haemopoietic has been studied at the EM level : it is characterized by numerous dense inclusions with pseudo-peroxidase activity and well developed granular endoplasmic reticulum and Golgi.

The authors consider the clinical and biological data of Acquired Idiopathic Sideroblastic Anemia (AISA). The physiopathology of the syndrome is discussed; the relationships between pathologic sideroblastosis, dyserythropoiesis and ferrokinetic modifications are pointed out. The associated abnormalities of granulocytic and megacaryocytic series linked AISA to other myelodysplasia.

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.

In our experimental conditions, the autoradiographic study of the 3H deltaaminolevulinic and 55Fe incorporation allows us to show selectively the red blood cells of Lineus lacteus actively synthetizing haemoglobin.

The authors consider the clinical and biological data of Acquired Idiopathic Sideroblastic Anemia (AISA). The physiopathology of the syndrome is discussed; the relationships between pathologic sideroblastosis, dyserythropoiesis and ferrokinetic modifications are pointed out. The associated abnormalities of granulocytic and megacaryocytic series linked AISA to other myelodysplasia.

The authors describe the case of a young Algerian, aged 32, suffering from mild icterus, accompanied by a marked splenomegaly. The blood count revealed a moderate degree of anaemia with reticulocytosis, pronounced anisocytosis, micro-spherocytes, bulls eye cells, folded cells, hypochrome cells, a marked polychromasia and a mild erythroblastosis. Present also were hyperbilirubinaemia, raised plasma haemoglobin, zero haptoglobin, a reduced osmotic fragility and half-life of erythrocytes. Haemoglobin electrophoresis showed 17.25% haemoglobin F, 62.8% haemoglobin C+A2 and no haemoglobin A. The genetic study indicated that the patient was a double heterozygote C/beta thalassaemia, his mother and his son both suffering from this disease. This thalassemic gene of type beta (0) totally inhibited the synthesis of haemoglobin A, the defect found in our patient.

During recent years, techniques of parenteral alimentation have seen the development of complications due to deficiencies in trace elements. The main deficiency states described involve iron, copper and zinc. In addition to these three trace elements, manganèse and cobalt are included in this study. The metabolism, physiological role, needs in parenteral alimentation and clinical and metabolic effects of possible deficiency are described for each of these elements.

The authors show that the, incubation techniques of reticulocytes, are able to appreciate accurately deficiency of the globin chain synthesis, so they allow to apply certainly diagnosis of thalassemias.