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Characterization of persulfate activation by solid iron was performed to determine kinetic parameters and control variables. The solid iron activated persulfate system was then used to demonstrate the degradation of the fluoroquinoline antibiotic ciprofloxacin. This study established the persulfate activation using solid iron takes place via a zero-order mechanism. Persulfate reaction rates were found to be linear functions of iron rod surface area, with a maximum reaction rate constant of 8.4 × 10−7 mol L−1 s−1 established at the highest iron rod surface area tested. Persulfate reaction rates increased with the current applied to an iron rod up to a current density of 8.2 mA cm−2 after which the rate plateaued. A maximum rate of 7.1 × 10−7 mol L−1 s−1 was established with applied current compared to 4.3 × 10−7 mol L−1 s−1 without current, when the same surface area of the iron rod was in solution. At a starting concentration of 0.121 mmol L−1, ciprofloxacin removal of 95% was achieved in 15 min. A ciprofloxacin transformation product matrix containing core quinolone structures was formed and then degraded by 90%, with total organic carbon removal of 44%. The corresponding defluorination was >95%, suggesting that solid iron activated persulfate may offer an advantage for destruction of some fluorinated compounds. Hydroxyl radicals were identified as the dominant radicals in the degradation process. Ciprofloxacin removal was independent of the applied current despite the increased persulfate activation under the same conditions.

Splenomegaly and splenic siderosis are well-known findings in beta-thalassemia major. We explored the relation between splenic size, splenic and hepatic siderosis in transfusion-dependent beta-thalassemic patients, assessed by MR imaging. Abdominal MR imaging studies of 47 consecutive thalassemic patients and 10 healthy subjects, used as controls, were retrospectively reviewed. The signal intensity ratios of spleen and liver to the right paraspinous muscle (S/M, L/M, respectively) were calculated on T1, intermediate, and T2*-weighted gradient-echo sequences, splenic volume was estimated on axial images and serum ferritin levels were recorded. Decreased S/M on all MR sequences was displayed in 36 patients. Six patients presented with normal S/M on all MR sequences and 5 patients displayed splenic hypointensity only on T2* sequence. No correlation between S/M and L/M was found whereas both L/M and S/M correlated with serum ferritin (P

Background Hepcidin-25, a central regulator of iron metabolism, can decrease serum iron levels by inhibiting the iron transporter ferroportin. Production of hepcidin-25 in hepatocytes is tightly regulated by various stimulations and is promoted by inflammation via the IL-6 pathway. The role of hepcidin-25 in acute infections has not been fully understood; therefore, we investigated the hepcidin and iron kinetics during the acute phase of systemic infection. Methods We collected clinical samples of bloodstream infections at various stages and measured plasma hepcidin-25 levels using surface enhanced laser desorption/ionization time-of-flight mass spectrometry. In addition, plasma levels of IL-6, C-reactive protein, procalcitonin, presepsin, lipocalin-2 were measured. Results In this study, 50 patients (median age: 72 years; 52% males) were included. In the acute phase of infection (first 3 days after onset of symptom), plasma hepcidin-25 levels were rapidly elevated, accompanied with a reduction in serum iron concentration. As the inflammation subsequently resolved and the patients’ general condition improved (≥10 days after symptom onset), serum hepcidin-25 levels were decreased and serum iron levels were restored. Therefore, hepcidin-25 and iron levels dynamically vary during the acute phase of infection, and the enhanced production of hepcidin-25 due to severe inflammation can precipitate a rapid decrease of serum iron levels. This series of reactions may be regarded as a host defense involving the inhibition of the nutrient acquirement of bacteria. In this setting, the iron requirement of bacteria is expected to be increased and the iron uptake of bacteria via iron transporter systems may be activated. Conclusion During the acute phase of infectious disease with severe inflammation, iron levels were immediately decreased due to enhanced production of hepcidin-25. Understanding of host iron status may be essential for effective use of siderophore cephalosporin, with a unique mechanism of action involving the use of bacterial iron uptake systems. Disclosures All authors: No reported disclosures.

Prevalence of iron defi ciency, physiologic role of iron in the organism, modern laboratory markers of iron kinetics, biochemical markers of iron defi ciency, classifi cation and clinical picture of iron defi ciency anemia, instrumental diagnostics, management of anemia according to severity and optimal schemes of prophylaxis are described in the article. Effi cacy and safety of different iron-contenting preparations, ways of their intake are shown. Control of МСН, MCV, МСНС is necessary for assessment of effi cacy of treatment. Normalization of those parameters refl ects the adequate therapy.

Ferrokinetic studies were carried out in 4 patients with Fanconi's anaemia (FA). Experimental data were analysed by means of a mathematical model of iron kinetics in order to obtain a quantitative assessment of effective and ineffective erythropoietic activity, mean red cell lifespan, and non-erythroid iron turnover. The major pathogenetic mechanism of the anaemia appeared to be relative marrow failure, i.e. a reduction in the proliferative capacity of the erythroid marrow. The role of ineffective erythropoiesis was of minor importance. On the basis of the results obtained both the pathogenesis and the natural course of the disease are discussed.

The prognostic significance of the bone marrow sideroblasts found in aregenerative anaemia with hypercellular bone marrow was evaluated particularly to see if the sideroblasts might be a preleukaemic sign. The study includes 32 patients with abnormal sideroblasts; 14 had mainly ringed sideroblasts while 18 had mainly the intermediate or ferritin type. Basic erythro-kinetic data (59Fe erythrocyte incorporation and erythroblast labelling indices) were similar in the two groups. The colony forming capacity (CFUC) was abnormal in 2 of 5 patients with ringed sideroblasts compared to 12 of 13 in the intermediate sideroblast group. Patients with mainly ringed sideroblasts had significantly longer duration of disease state, higher platelet and leucocyte counts, no increase in the percentage of bone marrow myeloblasts and did less often develop acute leukaemia. Thus aregenerative anaemias can be divided according to the type of abnormal sideroblasts in two groups with different risk of development of acute leukaemia. The ringed sideroblastic anaemia seems not to be a preleukaemic stage in the prospective sense in contrast to aregenerative anaemia with mainly intermediate sideroblasts.

Lactoferrin turnover was studied in the rabbit with 125I- and 131I-labelled human lactoferrin. Plasma lactoferrin activity showed a rapid decrease during the first 24 h, followed by a ‘final slope’ with a T1/2 of about 25 h. Turnover studies after transfer of plasma from one rabbit (A) 3 h after injection to another rabbit (B), showed a recovery of 100 % compared to 30 % in A rabbits but otherwise a similar disappearance curve. The rapid turnover was confirmed in whole body studies. Concomitantly with the initial disappearance from the plasma, there was a marked accumulation of protein bound activity only in the liver in both A and B rabbits. From these results, the rate of synthesis in normal man can be estimated at around 25 mg per d. The disappearance pattern and hepatic uptake are discussed in relation to knowledge about lactoferrin receptors in macrophages, asialo elimination, and fucose group recognition. Concerning the significance of lactoferrin turnover for iron metabollism it is concluded that the plasma turnover results are insufficient to explain the disturbance in iron kinetics seen in the anaemia of chronic disorders; however, it is likely that lactoferrin plays a role in iron metabolism within the extravascular space.

Hypoferremia is a well-known response to infections and inflammatory disorders. It seems to be managed by the key mediator of iron kinetics, hepcidin. There are several studies on induced-acute phase reactions. However, to our best knowledge there are no previous published reports on the outbreak of a common cold and its initial effect on iron kinetics. The objective of this case report is to describe such an observation. From an apparently healthy state in the morning we observed, in a 28-year-old male, every hour for 6 h the outbreak of a common cold and the modulations in the levels of serum iron (S-Fe) and interleukin-6 (IL-6). Despite a 100 mg oral iron loading there was a substantial reduction in S-Fe, which seemed to precede the IL-6 peak. Interestingly, this observed succession is in conflict with the proposed infection chain of order in which IL-6 stimulates hepcidin induction.

TNO Nutrition and Food Research Institute, AJ Zeist, The Netherlands.Iron absorption can be measured by the incorporation of stable iron isotopes into erythrocytes, 14 days after isotope administration. The disadvantage of this method is the high dose of isotopes needed to obtain a sufficient enrichment. Therefore, in this study cell fractions rich in young erythroid cells were prepared by using a density separation method. From 10 women blood was taken 4, 5, and 7 days after oral and intravenous administration of 57Fe and 58Fe. In these cell fractions and in whole blood taken 14 days after isotope administration, isotope enrichment was measured and absorption calculated. Absorption calculated from the isotope enrichment in the reticulocyte-rich cell fractions (12.2 +/- SEM 3.7%) was not significantly different from absorption based on whole-blood values (13.0 +/- 3.3%). Because a threefold higher isotope enrichment was found in the cell fractions, the required dose of stable isotopes can be reduced to one-third of the dose used in the traditional method without loss of sensitivity.

A trickle fixed-bed reactor model for the Fischer-Tropsch synthesis applicable to both cobalt and iron catalysts which accounts for gas and liquid recycle is described. A selection of kinetic models for both iron and cobalt catalysts (4 each) is included in the reactor model and their effect on model predictions is compared. While the model is 1-D and reaction rates are determined for quasi-average radial bed temperatures, a correlation is used to account for radial thermal conductivity and radial convective heat transfer. Traditional pressure drop calculations for a packed column were modified with a correlation to account for trickle-flow conditions. In addition to describing the model in detail and showing validation results, this paper presents results of varying fundamental, theoretically-based parameters (i.e. effective diffusivity, Prandtl number, friction factor, etc.). For example, the model predicts that decreasing effective diffusivity from 7.1E-09 to 2.8E-09 m2/s results in a lower maximum temperature (518 K vs. 523 K) and a longer required bed length to achieve 60% conversion of CO (8.5 m vs. 5.7 m). Using molar averages of properties to calculate the Prandtl number for the gas phase (recommended by the authors) results in average bed temperatures up to 10 K higher and reactor lengths 17-45% shorter than assuming a Prandtl number of 0.7. Using the Tallmadge equation to estimate friction losses, as recommended by the authors, results in a pressure drop 40% smaller than using the Ergun equation. Validation of the model was accomplished by matching published full-scale plant data from the SASOL Arge reactors.

Direct evidence of CNS developmental alterations in iron-deficient anaemic (IDA) infants was obtained. Twenty 3-15-month-old IDA and 20 non-IDA infants (age and gender matched), healthy in every other respect, were studied. Complete blood and iron kinetics tests determined an IDA status. Psychomotor development was assessed through the test of Rogers and co-workers [Rogers SJ, Donovan CM, D'Eugenio D, Brown SL, Whiteside E, Moersch MS, Schafer DS. (eds) Developmental Programming for Infants and Young Children, Vol 2. University of Michigan Press, 1981] and under the 10-20 International System qEEG was performed (sleep/stage II). A Pearson's correlation test was applied between haematological, psychomotor and broad band EEG variables, and through ANOVA psychomotor and AP means were compared. IDA infants showed lower scores in cognition, fine motor and social/emotional areas, higher delta/theta and lower alpha power. Most correlations between haematological/psychological variables were positive. Delta/theta correlations were negative with self-care/gross and motor items while alpha/beta AP showed positive correlations with psychomotor and haematological variables. A clear association was found between EEG alterations and a low haematological/iron profile leading to a delayed psychomotor development.

Iron absorption can be measured by the incorporation of stable iron isotopes into erythrocytes, 14 days after isotope administration. The disadvantage of this method is the high dose of isotopes needed to obtain a sufficient enrichment. Therefore, in this study cell fractions rich in young erythroid cells were prepared by using a density separation method. From 10 women blood was taken 4, 5, and 7 days after oral and intravenous administration of 57Fe and 58Fe. In these cell fractions and in whole blood taken 14 days after isotope administration, isotope enrichment was measured and absorption calculated. Absorption calculated from the isotope enrichment in the reticulocyte-rich cell fractions (12.2 ± SEM 3.7%) was not significantly different from absorption based on higher isotope enrichment was found in the cell fractions, the required dose of stable isotopes can be reduced to one-third of the dose used in the traditional method without loss of sensitivity.

Serum and erythrocyte ferritin concentrations were measured in 369 healthy term neonates and their mothers, with a view to understanding maternofetal iron kinetics. Erythrocyte ferritin concentrations in the neonates were on average 100 times higher than maternal values, while those of serum ferritin were about 10 times higher. Maternal and fetal iron status were correlated in the overall study population. Serum and erythrocyte ferritin values were also correlated with each other in both the mothers and neonates. To study the influence of iron status on these conditions, we formed three groups of mother-child pairs of equal size, based on maternal iron status (serum ferritin). The correlations found in the overall population were not always present in each subgroup. In the infants born to mothers with adequate tissue iron reserves (serum ferritin > 12 micrograms/I), a statistical link was found between serum and erythrocyte ferritin levels. When the mothers had optimal iron status (serum ferritin > or = 22 micrograms/I), there was a correlation between the neonatal and maternal erythrocyte ferritin levels. No such links were found when the mothers had low tissue iron stores (serum ferritin < 12 mg/I). These data point to special iron kinetics during fetal life and the influence of maternal iron status.

Summary. A colloidal suspension of hydrolysed radio-iron of high specific activity has been developed for the investigation of reticuloendothelial (RE) iron kinetics in man. Following intravenous injection this material is cleared rapidly by the RE system and the iron released into the plasma where it is bound to transferrin. There is no significant addition to the endogenous RE iron load, and it has proved possible to measure RE iron release without disturbing the normal iron flow.

Rats were irradiated with one tibia shielded (95% marrow exposure), total body exposed (TBI, 100%), and only one tibia exposed (5%), or they were sham irradiated (SI, 0%). Plasma Fe-59 clearance time (T 1/2) and Fe-59 content ratio in the right and left tibia (RT/LT) were assayed to determine the erythroid activity of the overall marrow of the animals and the relative marrow activity in the exposed and shielded tibias, respectively. When a major fraction of the overall marrow was shielded or irradiated, the overall erythroid activity levels were identical to those of the SI and TBI animals, respectively. Interestingly, enhanced normoblastosis was observed in the marrow of the exposed tibia of individual animals exhibiting normal erythroid activity in 95% of the marrow. Conversely, localized marrow with normal erythroid activity was found in a shielded tibia of individual rats, demonstrating an enhanced erythroid activity in a major fraction of the total body. It was concluded that 88 mrad can alter marrow functions in a small isolated skeletal region as effectively as in the whole body, and tandem assays of the Fe-59T 1/2 and Fe-59 RT/LT can facilitate ultra-low-dose X-ray studies involved with partial body exposures.

A simple method for determining the hardness or thickness of very thin (few micrometre) ceramic coatings is described. The methods employed are demonstrated for hard, thin coatings of titanium nitride, deposited by physical vapour deposition on to high speed steel substrates. A procedure has been formulated, using the microhardness technique, to carry out thickness, hardness, and adhesion quality control checks on coated items.

Ferrokinetic and RBC mass determinations were made at 3-month intervals in iron-replete hemodialysis patients randomized to a control group or to nandrolone decanoate therapy. After 3 months, RBC mass increased in two of 4 androgen-treated patients. Erythron iron turnover, an index of RBC production, increased in the one responder studied but not in the two nonresponders. Similarly, in a fifth subject, who was not restudied until 6 months of androgen therapy were completed, an increase in RBC mass was associated with an increase in erythron iron turnover. However, between 3 and 6 months, RBC mass increased in all 4 androgen-treated patients studied even though erythron iron turnovers remained unchanged and dialysis-associated blood losses did not decrease. Thus, at least two androgen-treated patients had increases in RBC mass without ever increasing their erythron iron turnover. Two of three control subjects also had increased erythron iron turnovers, which in one case was related to increased dialysis-associated blood losses. Changes in RBC mass were not consistently paralleled by changes in Hb. These findings suggest that increases in RBC mass during nandrolone decanoate therapy result from two mechanisms: increased erythropoiesis (shown by simultaneous increases in RBC mass and erythron iron turnover) and increased RBC survival (indirectly shown by increases in RBC mass without increases in erythron iron turnover). The importance of control groups, RBC mass determinations and the monitoring of dialysis-associated blood losses in studying the effects of androgens on erythropoiesis in chronic hemodialysis patients is also demonstrated.

Vacha, J. V. Znojil, Jirina Hola, J. Dungel: Iron Kinetics in Individual Bone Marrow Regions (Bones) in Mice. Acta vet. Brno, 53, 1984: 119-136. The course of concentration of labelled iron (.oFe) after its intravenous admi­ nistration was observed experimentally in plasma, erythrocytes, spleen and indi­ vidual bones (here in haem and non-haem fraction separately). The optimum number of iron compartments in individual bones and the constants characterizing the flow through these compartments was then sought by means of mathematical mo­ delling. It was possible to type the compartments by comparing flows into the bones of various types and to try to find their physiological interpretation. The following compartments were determined (apart from the circulating plasma and erythrocytes): 1. An iron pool with a half-time of efflux of several tens of minutes to several hours, probably corresponding to the iron contained in the interstitial marrow and splenic spaces, in a rapidly assumed equilibrium with plasma; 2. An iron pool with a half-time of efflux about nine hours, corresponding to the iron incorporating into haem or deposited in the pre-haem pool in erythroblasts; 3. An iron pool with a half-time of efflux of about 1-3 days, having the character of stores, probably deposited both in erythroblasts (half-time 3.15 days) and in cellular elements of the haematopoietic microenvironment (half-time 1.65 days); 4. An iron pool bound in the long-term in the teeth. The bones could be divided according to the represen­ tation of compartments into three groups: 1. Long bones and spine, in which inten­ sive erythropoiesis takes place, exhausting the interstitial pool and consuming most of the storage iron pool; 2. Acral bones and the skull, with minimal erythropoiesis, in which the dynamics of the interstitial and storage iron pool localized beyond erythroblasts predominantly occurs; 3. Thoracic bones, representing a group inter­ mediate between the two former ones in several aspects. - The model is also in accordance with the independently (chemically) ascertained iron content in the bones. The results represent a considerable refinement of our general model of ferro­ kinetics in mice (Vacha et al. 1982) and provide a firmer basis for the study of ferrokinetics in bone marrow under pathological states of erythropoiesis. Studies of this type are an inevitable prerequisite of correct interpretation of the labelled iron incorporation method as an indicator of the intensity of erythropoiesis. Ferrokinetics, iron compartments in bones of various types, haem and non-haem iron, .oFe-incorporation method. Knowledge of the internal exchange of iron in an organism is a prerequisite for the correct interpretation of the commonly used method of labelled iron incorporation into the erythropoietic organs. The internal iron kinetics in mice are, however, known only incompletely as yet. In our previous paper (Vacha et al. 1982) we proposed a model of the ferrokinetics of mice encompassing the sizes of basic iron compartments in the erythropoietic organs, the blood and the liver and the extent of flows between them. The employment of a model of ferrokinetics for the study of erythro­ poiesis presupposes, however, an analysis of iron compartments in the bone marrow more sophis­ ticated than that which can be made in such a general model. The basic idea of the present paper

Summary. Erythrokinetic parameters were estimated in six patients suffering from congenital dyserythropoietic anaemia type II (CDA II) by means of a mathematical model of iron kinetics. A wide variation in effectiveness of erythroid activity was observed, and a significant negative correlation was found between ineffective erythropoiesis and peripheral haemolysis. In four patients with prominent peripheral haemolysis, splenectomy was carried out. Marked improvement in their clinical condition and in haemoglobin level resulted.

Summary. Iron metabolism in the rat has been examined by chemical and isotopic measurements. Iron stores were larger in the female than the male, but in neither sex did stores play a dominant role in meeting increased iron needs. A nearly two-fold higher plasma iron turnover in growing rats as compared with adult animals was accounted for largely by growth requirements. In both sexes and in both young and adult rats, the erythroid marrow assimilated more than two-thirds of the plasma iron turnover. The source and distribution of transferrin iron was assessed in relation to the erythroid marrow, gastrointestinal tract, hepatic parenchyma and remaining body tissues. Absorption from the gastrointestinal tract provided about one-third of the iron entering the plasma in adult rats and more than half in growing or phlebotomized rats. Iron absorption was closely related to the erythroid marrow requirements, but did not correlate with either the plasma iron level or tissue iron stores. The rat depends on dietary iron rather than iron stores to meet increased requirements and shows a much greater capacity to absorb iron than does man.

A useful stochastic model of iron kinetics is examined in terms of a mathematically equivalent multicompartment model. Although this model oversimplifies the process by which iron moves from the plasma to circulating red blood cells, it accurately describes iron kinetics under a variety of circumstances. Parameters of this compartment model are shown to be uniquely identifiable. A D -optimal ferrokinetic blood-sampling schedule based on the model achieves a 33% increase in efficiency over a schedule commonly used.

Summary Erythrokinetic parameters were estimated in 21 patients suffering from haemolytic disease using a mathematical model of iron kinetics. A proper definition of radioiron reflux from red cells to the plasma proved to be essential for an accurate estimate of effective and ineffective erythropoiesis in severe haemolytic conditions. Erythropoietic activity was increased in all the patients, with the marrow capable of sustaining erythropoiesis at about 6 times normal in hereditary spherocytosis and 3 times normal in autoimmune haemolytic anaemia. This proliferative effort was countered by an increase in ineffective erythropoiesis which was especially marked in hereditary spherocytosis.

Ferrokinetic parameters were estimated in eight patients with primary acquired sideroblastic anaemia (PASA) by means of a mathematical model of iron kinetics. Both plasma 59Fe clearance and red cell utilization curves were used to identify the model parameters. The close agreement between experimental and theoretical data proved that the model can describe iron kinetics in sideroblastic anaemia. Ineffective erythropoiesis was found to be the major factor in the production of the anaemia. Various degrees and patterns of peripheral haemolysis were observed. The storage iron was always markedly increased and a large non-erythroid iron turnover was calculated in the most severely affected patients. The results are compared with present knowledge of erythropoiesis in PASA.

Vacha J., V. Znojil, J. Hola, J. Dungel: The Internal Iron Kinetics in Mice. Acta vet. Bmo, 51, 1982: 3-22. Using mice of the strain C57BL/I0ScSnPh a three-week study was made of radio­ activity in the plasma, erythrocytes, liver and haeme and non-haeme iron of the bone marrow and spleen, and of the urine and faeces following·oPe administration. On the basis of the experimental data obtained a mathematical model was used to determine the rates of flows between the assumed iron compartments of the organism. By means of the chemical determination of the haeme and non-haelne iron of these or­ gans it was possible to express these flows in absolute values, thus forming an over­ all model picture of the ferrokinetics of mice. It is clear from the model that the central ferrokinetic pool in mice consists not only of the plasma but also of a further space of considerable size and rate of exchange, identifiable with considerable certainty with the extravascular and lymphatic spaces. Non-haeme pools of considerable sizes were also found in the erythropoietic organs. The one with the faster rate of exchange has a mostly pre-haeme character; the se­ cond, of approximately ten times the size, characterized by a slower rate of exchange, does not have any immediate relation as a whole to erythropoiesis and is thus the main cause of discrepancies between the results of ··Pe incorporation into the erythropoie­ tic organs and the actual intensity of erythropoiesis. Ferrokinetics, iron compartments, haeme and non-haeme iron, bone marrow, spleen, .oFe-incorporation method.

SummaryA new case of primary hemorrhagic thrombocythemia is presented, in which ferrokinetic studies were performed 3 times in different phases of the illness.The 84 years old patient fitted all the clinical and hematological criteria of these disease : repeated spontaneous hemorrhages, splenomegaly, persistent thrombocythemia, severe and prolonged anemia, leukocytes not in excess of 50.000 and a rich bone marrow with pronounced megakaryocytic preponderance.Radioactive phosporous treatment produced several remissions, but the patient died 2 years after the diagnosis was established, showing a transformation to acute monocytic leukemia.The quantitative determinations of iron kinetics in the hemorrhagic phase, in remission and in hematologic relapse showed an highly increased erythropoiesis despite of the existent anemia and an important ineffective erythropoiesis.Therefore, the authors feel that primary hemorrhagic thrombocythemia is a myeloproliferative disorder with a predominant platelet elevation.

1. 1. Iron kinetics was studied on Siredon mexicanum originally from the valley of Mexico (7343 ft). 2. 2. Plasma iron clearance (T 1 2 59 Fe) was estimated in 150 min. Circulating red-cells uptake was about 35 per cent. 3. 3. 59 Fe bone marrow uptake had a peak after 2 hr of the radioisotope injection, with a later decrease. Spleen and liver increased their uptake up to a maximum between the first and the fifth day, with also a later decrease. 4. 4. It is concluded that mainly the spleen and in a lesser degree the liver and bone marrow are the most important organs of red-cell production in this animal. 5. 5. On the basis of the results obtained, we were able to compare axolotl erythropoiesis with that of the human foetus during the fourth to sixth lunar month of intra-uterine life.

Effective erythroid marrow activity was quantitated by reticulocyte counts and iron kinetics in normal individuals and in 50 patients suffering from various haematological disorders. To allow direct comparison between both measurements normal base line values were established and defined as production index 1. The erythrocyte iron turnovers as calculated from plasma iron turnover and radioiron red cell incorporation were divided by the figure found in normal subjects, 0.49 mg per 100 ml whole blood per day. Reticulocyte percentages were first corrected for changing haematocrit levels considering as normal 1 and 45% respectively. In this form reticulocyte counts overestimated effective red cell production in the majority of anaemic patients. Further correction was needed to account for the well known inverse temporal relationship between the erythropoietin-induced marrow transit acceleration and the prolonged maturation period of circulating reticulocytes. For this purpose the haematocrit-corrected reticulocyte counts were divided by the fraction marrow transit time normal (3.5 days)/marrow transit time patient. This parameter is defined as the time period necessary for 50% appearance of maximum cellular activity. Now production indices derived from the 2 methods agreed almost perfectly. Marrow transit times were related to characteristics of the peripheral blood film, i.e. polychromasia and mean morphological reticulocyte maturation stage. On this basis guidelines were worked out for a meaningful interpretation of reticulocyte counts.

The hematopoietic effects of both single and repeated intravenous injections of moderate concentrations of Vincristine Sulfate on rabbit erythropoiesis have been presented. A prompt depopulation of erythroid elements results and is almost completed by 48 hours. Following this depression a rapid rebound of erythropoietic activity occurs. Serum iron values reflect these changes in iron utilization. The reproducibility of these extremes in marrow erythropoietic activity allows one to use the Vincristine Sulfate treated rabbit as an experimental model. It will allow us to study the factors which regulate the balance between erythropoiesis and iron kinetics.

Summary. The clearance of transferrin-bound iron from the interstitial fluid of skin has been measured in normal and iron-deficient subjects. It is possible to interpret the results by means of a two-compartment model and to calculate the rate of entry and exit of iron in skin cells. There is a decrease in the amount of iron entering skin cells in patients with iron-deficiency anaemia. The demonstration of an intracellular exchangeable iron pool in the skin suggests that there may also be large parenchymal pools in other organs, which are indirectly in equilibrium with the plasma pool.

Gli AA. mostrano alcuni esempi di applicazioneoff- line delcomputer nel campo della medicina nucleare. Essi si riferiscono al calcolo giornaliero dell’attivita specifica e dei volumi dei traccianti marcati, allo studio e graficazione della ferrocinetica nel sangue, della sopravvivenza delle emazie marcate con radiocromo e della captazione tiroidea dello iodio. Un breve cenno e riservato alla refertazione automatica. Vengono messi in evidenza la facilita d’impiego dei programmi mediante telescrivente collegata ad uncomputer e i vantaggi in risparmio di tempo da parte del personale e in correttezza di esecuzione delle metodologie.

The mathematical model here presented of steady-state iron kinetics in the human explicitly displays the influence of the maturative and proliferative behavior of erythrons (erythrocytes or their precursory cells). Based on a compartmented iron kinetics scheme, the model is in the form of a system of linear integrodifferential equations and describes the distribution of administered radioactive tracer as a function of time. Erythron behavior is characterized by three functions specifying iron uptake, proliferation, and survival. Simulative uses of the model are discussed and illustrated by an example.

In 15 blood and plasma donors kinetics of radioactive iron was determined. Decreased body iron content was found in most [11] subjects, in two of them it was associated with reduction in the mean survival time of erythrocytes. Iron deficiency was greatest in the group of donors with a history of multiple blood donations during many years. Anaemia was not found in any case and 24-hour synthesis of haemoglobin was normal in all donors; in 3 cases it was even raised.

Computer methods for analysis of iron kinetics on the basis of specified models are presented. One method is based on direct simulation of the processes in the model, whereas the other method uses a standard fourth-order Runge - Kutta integration of the system of differential equations describing the model.