Utilization of Iron Dextran

The utilization of iron dextran was investigated in normal subjects, in patients with iron-deficiency anaemia, and in anaemias associated with rheumatoid arthritis, reticulosis, and uraemia. Utilization of iron for haemoglobin formation at 14 days was found to be depressed in patients with rheumatoid arthritis, reticulosis, and uraemia, but when a concomitant iron-deficiency anaemia was present utilization was significantly increased. When iron dextran is used to treat anaemias in such conditions an optimum therapeutic response will be obtained only when bone marrow iron stores are absent.     

Evidence for Various Types of Synthesis of Human γ Chains of Haemoglobin in Acquired Haematological Disorders

AT first, the γ chain of human haemoglobin seemed to be a constant chemical species¹, but Schroeder et al. showed that two or possibly four of the γ chain loci which control the synthesis of the two types of chains, ^Aγ and ^Bγ, are active in new born infants². The two chains differ only at position 136, where ^Aγ has alanine and ^Gγ has glycine. Thus although they are inseparable by chromatography and electrophoresis, their relative concentrations can be estimated from the ratio of these two amino-acids in the third and last peptide (γ^CB3) produced by hydrolysis of the chains by cyanogen bromide. Schroeder et al. studied the variations in the levels of these two chains during the normal ontogenic development and in several cases of hereditary persistence of foetal haemoglobin (HPHF) and β thalassaemias^3–5. We have studied the γ chains synthesized in different types of acquired anaemia with increased amounts of foetal haemoglobin, of which haemoglobin F constitutes between 1 and 15%. Such anaemias include refractory anaemias with excess myeloblasts (RAEM), acquired sideroblastic idiopathic anaemias (ASIA), idiopathic aplastic anaemias and some varieties of leukaemias, especially juvenile myeloid leukaemias (JML).     

Optimizing the diagnosis of anemia

The specific value of the erythrocyte parameters MCH and MCV for the differential-diagnostic arrangement of anaemias to the use of the haematological automations of analysis PHA 1/2 is represented. A prerequisite is the precise determination of haemoglobin concentration and erythrocyte number. MCHC has no sufficient discriminatory capacity.     

Haptoglobin in various diseases]

The clinical significance of haptoglobin (Hp) can be seen in the fact that its serum concentration shows a specific pattern in certain diseases and under various therapeutic measures. The determination of Hp is not only indicated in haemolytic anaemias, but also in liver and kidney diseases, infections, diseases of the connective tissue, malignant tumours, and under certain therapeutic conditions.     

Parvovirus B 19 infections

We report the human parvovirus (HPV) infection cases diagnosed in 1984 and 1985 in the virological laboratory of C.N.T.S. Detection of viral antigen and total anti-HPV antibodies was performed by electroimmunodiffusion, and specific IgM by antibody-capture-radioimmunoassay. Seven viraemias were found in 38,730 sera sent for detection of hepatitis A and B markers. Twenty-two observations of aplastic crisis are described, with underlying haemolytic anaemias in 21 cases. HPV infection was serologically proven in 4 cases out of 22 rubeolelike illness, and, in 17 cases out of 17 erythema infectiosum (fifth disease). Four cases of vascular purpura (one of which was Schonlein-Henoch purpura) were studied, and HPV antigen was isolated in 2 cases. An observation of arthropathies in a young adult is described. Finally, 2 spontaneous abortions were simultaneous to an HPV infection. Our study allows us to underline the following points: HPV is the principal (but not exclusive) agent of the aplastic crisis in chronic haemolytic anaemias; these acute erythroblastopenias can reveal an unknown haemolytic anaemia, in particular in hereditary spherocytosis; the polymorphism of the clinical expression of HPV infection is important. Some viraemias are asymptomatic, while others are accompanied by vascular purpura, or atypic erythema; HPV has never been isolated in the fifth disease. Nonetheless bringing out of specific IgM and association of HPV infection linked manifestations in a same patient or in a same family shows its responsibility in the fifth disease; HPV responsibility in spontaneous abortions and fetal malformations remains to be demonstrated.     

Absorption and Utilization of Polyglutamyl Forms of Folate in Man

Some three-quarters of folate compounds in a normal mixed diet have a chain of seven glutamic acid residues (polyglutamates). The extent to which these forms of folate are absorbed and utilized by man is of considerable nutritional importance. These studies indicate that the polyglutamate forms were absorbed and utilized to about one-third of the extent of simpler (monoglutamate) forms, as judged by the serum folate levels after oral equimolar doses, by the amount incorporated into red cells in long-term studies, by the amount excreted into the urine, and by their capacity to initiate haematological responses in patients with folate-deficient megaloblastic anaemias.     

Membrane proteins in hereditary spherocytosis, elliptocytosis and stomatocytosis

Cell membrane proteins of patients with hereditary spherocytosis, elliptocytosis and stomatocytosis were analyzed by SDS acrylamide gel electrophoresis. From 7 patients with hereditary spherocytosis only one can be supposed to have a reduction of a band with a molecular weight of about 80,000 daltons. 3 members of a family with hereditary elliptocytosis and 1 patient with hereditary stomatocytosis did not differ from the donors. The question of the nature of membrane defect in haemolytic anaemias could not be answered by the results obtained.     

Red blood cells

Red blood cells are derived from haemopoietic stem cells in bone marrow. Following a series of maturation steps, directed largely by the hormone erythropoietin (Epo), red cells enucleate and enter the circulatory system. In circulation these small, flexible biconcave cells containing haemoglobin transport O₂ from the lungs to the periphery, and CO₂ back from the periphery to the lungs. The most common disorders associated with red blood cells are anaemias. While there are numerous causes of anaemia, the reduced capacity for gaseous exchange is the underlying theme. Over the past 15 years, recombinant Epo has been used extremely successfully in the treatment of several forms of anaemia. The single gene disorders collectively known as haemoglobinopathies represent one of the best opportunities for gene therapy.     

Hepatic iron deposition in human disease and animal models

Iron deposition occurs in parenchymal cells of the liver in two major defects in human subjects (i) in primary iron overload (genetic haemochromatosis) and (ii) secondary to anaemias in which erythropolesis is increased (thalassaemia). Transfusional iron overload results in excessive storage primarily in cells of the reticule endothelial system. The storage patterns in these situations are quite characteristic. Excessive iron storage, particularly in parenchymal cells eventually results in fibrosis and cirrhosis. There is no animal model or iron overload which completely mimics genetics haemochromatosis but dietary iron loading with carbonyl iron or ferrocene does produce excessive parenchymal iron stores in the rat. Such models have been used to study iron toxicity and the action of iron chelators in the effective removal of excessive iron stores.     

Review. Leaky Cl--HCO3- exchangers: cation fluxes via modified AE1

The abundant membrane protein AE1 normally functions as an obligate anion exchanger, with classical carrier properties, in human red blood cells. Recently, four single point mutations of hAE1 have been identified that have lost the anion exchange function, and act as non-selective monovalent cation channels, as shown in both red cell flux and oocyte expression studies. The red cell transport function shows a paradoxical temperature dependence, and is associated with spherocytic and stomatocytic red cell defects, and haemolytic anaemias. Other forms of AE1, including the native AE1 in trout red cells, and the human mutation R760Q show both channel-like and anion exchange properties. The present results point to membrane domains 9 and 10 being important in the functional modification of AE1 activity.     

The oxygen transport function of the blood and of the erythrocyte concentrate during storage and its importance for blood transfusion

The property of oxygen transport function was investigated in blood which had been stored in solutions of "glugizir" and "zitroglucophosphate" and in erythrocyte concentrates gained from it on the noughth, 7th, 14th und 21st day of storage at -4 +/- 2 degrees C. The parameters of the oxygen binding function (oxygen content of erythrocytes, half time of haemoglobin saturation with oxygen, concentration of organic phosphate [2.3 diphosphoglycerate and adenosine triphosphate] and those of inorganic phosphorus were determined in erythrocytes. During storage for more than 21 days no significant differences could be detected in the property of oxygen transfer between erythrocytes of stored blood and erythrocyte concentrate, with the values for storing in zitroglucophosphate being somewhat higher. Problems of applying all components of donor blood efficiently are discussed. In performing an adequate haemotherapy with blood components the importance of a functional condition of erythrocytes and oxygen balance in the organism of the receiver should be considered. The necessity of transfusing erythrocyte concentrate in the therapy of anaemias of different genesis is emphasized and the differences in applying concentrates in different plasma solutions are referred to. By transfusing concentrates the effectiveness of hemotherapy are elevated and the rate of complications and side-effects of whole blood are diminished.     

Evaluating the success of blood transfusion with erythrocytes preserved in different ways

In a clinical study 18 patients with an indication to polytransfusion were examined by reason of secondary anaemias in diseases of the haemopoietic system. The efficiency of transfusion on the basis of body height, body mass and sex of the patients and the blood volume resulting from it as well as the exact amount of haemoglobin provided by stored blood and the increase of HB post transfusionem connected with it were found to be the criteria for the success of a transfusion. However, selected clinical parameters (LDH, Hbe, potassium, bilirubin) were constantly checked. The following values for the average efficiency of transfusion were found 16 hours post transfusionem: in washed erythrocyte concentrate 77%; in erythrocyte concentrate c. b. c. 45%; in erythrocyte concentrate GK 36%. Therefore, special emphasis is placed on an accompanying control of haemotherapy.     

Plasma transcobalamins in haematological disorders

Plasma UBBC-B12 and transcobalamins were measured in 112 patients suffering from different haematological disorders. The data showed different patterns of changes in plasma transcobalamin profile in different haematological disorders. Plasma UBBC-B12 and transcobalamins were significantly higher than normal in untreated chronic myeloid leukaemia, acute promyelocytic leukaemia, nutritional megaloblastic anaemia and in refractory anaemias with hypercellular marrow. Normal levels of these proteins were noted in chronic lymphatic leukaemias, in primary and secondary hypereosinophilic states and in multiple myeloma. Subnormal levels of these proteins were observed in hypoplastic anaemia and acute lymphoblastic leukaemia. Chronic myeloid leukaemia patients during blast crisis and acute myeloid leukaemia patients except those suffering from acute promyelocytic leukaemia showed varying pattern of plasma transcobalamins depending on type of blast crisis or FAB subtype of AML. The significance of these changes in plasma transcobalamins have been discussed along with the experience of other workers in this field.     

Iron mobilization using chelation and phlebotomy

Knowledge of the basic mechanisms involved in iron metabolism has increased greatly in recent years, improving our ability to deal with the huge global public health problems of iron deficiency and overload. Several million people worldwide suffer iron overload with serious clinical implications. Iron overload has many different causes, both genetic and environmental. The two most common iron overload disorders are hereditary haemochromatosis and transfusional siderosis, which occurs in thalassaemias and other refractory anaemias. The two most important treatment options for iron overload are phlebotomy and chelation. Phlebotomy is the initial treatment of choice in haemochromatosis, while chelation is a mainstay in the treatment of transfusional siderosis. The classical iron chelator is deferoxamine (Desferal), but due to poor gastrointestinal absorption it has to be administered intravenously or subcutaneously, mostly on a daily basis. Thus, there is an obvious need to find and develop new effective iron chelators for oral use. In later years, particularly two such oral iron chelators have shown promise and have been approved for clinical use, namely deferiprone (Ferriprox) and deferasirox (Exjade). Combined subcutaneous (deferoxamine) and oral (deferiprone) treatment seems to hold particular promise.     

The role of oxidative stress in hemolytic anemia

The oxidative status of cells is determined by the balance between pro-oxidants and antioxidants. Pro-oxidants, referred to as reactive oxygen species (ROS), are classified into radicals and nonradicals. The radicals are highly reactive due to their tendency to accept or donate an electron and attain stability. When cells experience oxidative stress, ROS, which are generated in excess, may oxidize proteins, lipids and DNA - leading to cell death and organ damage. Oxidative stress is believed to aggravate the symptoms of many diseases, including hemolytic anemias. Oxidative stress was found in the beta-hemoglobinopathies (sickle cell anemia and thalassemia), glucose-6-phosphate dehydrogenase deficiency, hereditary spherocytosis, congenital dyserythropoietic anaemias and Paroxysmal Nocturnal Hemoglobinuria. Although oxidative stress is not the primary etiology of these diseases, oxidative damage to their erythroid cells plays a crucial role in hemolysis due to ineffective erythropoiesis in the bone marrow and short survival of red blood cells (RBC) in the circulation. Moreover, platelets and polymorphonuclear (PMN) white cells are also exposed to oxidative stress. As a result some patients develop thromboembolic phenomena and recurrent bacterial infections in addition to the chronic anemia. In this review we describe the role of oxidative stress and the potential therapeutic potential of anti-oxidants in various hemolytic anemias.     

Haematology of the australian eastern quoll,Dasyurus viverrinus

• 1.1. A variety of haematological parameters were determined in adult Dasyurus viverrinus.
• 2.2. Haemoglobin and red cell counts were high with a very low mean cell volume.
• 3.3. Basophils are absent but the eosinophils contain small numbers of basophilic granules which may indicate a dual role for this cell.
• 4.4. “Ring Form” leucocytes are present.
• 5.5. Three types of red cell picture could be identified, some animals showing large numbers of spherocytes, spicule cells, and inclusion bodies.
• 6.6. These cells resemble those found in some inherited human haemolytic anaemias but there was no evidence of haemolysis in the animals.
• 7.7. An alkali resistant haemoglobin component is present.

     

Ascorbate removes key precursors to oxidative damage by cell-free haemoglobin in vitro and in vivo

Haemoglobin initiates free radical chemistry. In particular, the interactions of peroxides with the ferric (met) species of haemoglobin generate two strong oxidants: ferryl iron and a protein-bound free radical. We have studied the endogenous defences to this reactive chemistry in a rabbit model following 20% exchange transfusion with cell-free haemoglobin stabilized in tetrameric form [via cross-linking with bis-(3,5-dibromosalicyl)fumarate]. The transfusate contained 95% oxyhaemoglobin, 5% methaemoglobin and 25 microM free iron. EPR spectroscopy revealed that the free iron in the transfusate was rendered redox inactive by rapid binding to transferrin. Methaemoglobin was reduced to oxyhaemoglobin by a slower process (t(1/2) = 1 h). No globin-bound free radicals were detected in the plasma. These redox defences could be fully attributed to a novel multifunctional role of plasma ascorbate in removing key precursors of oxidative damage. Ascorbate is able to effectively reduce plasma methaemoglobin, ferryl haemoglobin and globin radicals. The ascorbyl free radicals formed are efficiently re-reduced by the erythrocyte membrane-bound reductase (which itself uses intra-erythrocyte ascorbate as an electron donor). As well as relating to the toxicity of haemoglobin-based oxygen carriers, these findings have implications for situations where haem proteins exist outside the protective cell environment, e.g. haemolytic anaemias, subarachnoid haemorrhage, rhabdomyolysis.     

Increasing oxygen radicals and water temperature select for toxic Microcystis sp

Pronounced rises in frequency of toxic cyanobacterial blooms are recently observed worldwide, particularly when temperatures increase. Different strains of cyanobacterial species vary in their potential to produce toxins but driving forces are still obscure. Our study examines effects of hydrogen peroxide on toxic and non-toxic (including a non-toxic mutant) strains of M. aeruginosa. Here we show that hydrogen peroxide diminishes chlorophyll a content and growth of cyanobacteria and that this reduction is significantly lower for toxic than for non-toxic strains. This indicates that microcystins protect from detrimental effects of oxygen radicals. Incubation of toxic and non-toxic strains of M. aeruginosa with other bacteria or without (axenic) at three temperatures (20, 26 and 32°C) reveals a shift toward toxic strains at higher temperatures. In parallel to increases in abundance of toxic (i.e. toxin gene possessing) strains and their actual toxin expression, concentrations of microcystins rise with temperature, when amounts of radicals are expected to be enhanced. Field samples from three continents support the influence of radicals and temperature on toxic potential of M. aeruginosa. Our results imply that global warming will significantly increase toxic potential and toxicity of cyanobacterial blooms which has strong implications for socio-economical assessments of global change.     

The ecological significance of toxic nectar

Although plant-herbivore and plant-pollinator interactions have traditionally been studied separately, many traits are simultaneously under selection by both herbivores and pollinators. For example, secondary compounds commonly associated with herbivore defense have been found in the nectar of many plant species, and many plants produce nectar that is toxic or repellent to some floral visitors. Although secondary compounds in nectar and toxic nectar are geographically and phylogenetically widespread, their ecological significance is poorly understood. Several hypotheses have been proposed for the possible functions of toxic nectar, including encouraging specialist pollinators, deterring nectar robbers, preventing microbial degradation of nectar, and altering pollinator behavior. All of these hypotheses rest on the assumption that the benefits of toxic nectar must outweigh possible costs; however, to date no study has demonstrated that toxic nectar provides fitness benefits for any plant. Therefore, in addition to these adaptive hypotheses, we should also consider the hypothesis that toxic nectar provides no benefits or is tolerably detrimental to plants, and occurs due to previous selection pressures or pleiotropic constraints. For example, secondary compounds may be transported into nectar as a consequence of their presence in phloem, rather than due to direct selection for toxic nectar. Experimental approaches are necessary to understand the role of toxic nectar in plant-animal interactions.     

Toxicity of secondary compounds to the seed-eating larvae of the bruchid beetle Callosobruchus maculatus

By incorporating various secondary compounds in the normal diet of larval Callosobruchus maculatus bruchids, we show that the effects of any particular compound are dosage-dependent. Alkaloids are generally the most toxic of the compounds tested. Non-protein amino acids are more toxic than protein amino acids but the latter can be toxic at 1 and 5% incorporation in the diet. The non-protein amino acid homoarginine has a salutary effect on larval survival at low concentrations. A variety of other secondary compounds found in seeds are toxic at various levels representative of those levels found in seeds in nature, and for all secondary compounds tested a 0.1–5% incorporation in the diet often has a detrimental effect on production of adult beetles. We conclude that many of the secondary compounds found in seeds are likely to be toxic to at least some animal, and thus are likely to be responsible at least in part for the extreme host-specifity shown by seed-eating insects.