Biomedical subjects

I Klonizakis

Publications and source records attributed to I Klonizakis.

9 recordsLinked to original sources

PubMed1997

Responsiveness to recombinant human erythropoietin (rh-Epo) of marrow erythroid progenitors (CFU-E and BFU-E) from B-chronic lymphocytic leukemia (B-CLL).

The responsiveness of bone marrow erythroid progenitors (CFU-E and BFU-E) to various concentrations of recombinant human erythropoietin (rh-Epo) (2,5,20,40,100,200 and 500 U/ml) was investigated in vitro in 18 patients with B-chronic lymphocytic leukemia to assess the clinical usefulness of rh-Epo in this disease. Bone marrow mononuclear cells were cultured by methylcellulose methods for CFU-E and BFU-E assays. The B-chronic lymphocytic leukemia patients were divided into two groups according to the percentage of lymphocytes in the bone marrow (under 70% and over 70%). Among the patients with few lymphocytes, more than one third demonstrated some degree of response to rh-Epo. Among the patients with a high percentage of lymphocytes in the bone marrow, some revealed no response to rh-Epo, but there were patients who showed a good response to rh-Epo. Because erythroid progenitors from B-chronic lymphocytic leukemia appeared sensitive to rh-Epo in vitro, we propose that high doses of this drug may be clinically effective in some patients with this disease, regardless of the degree of lymphocytic inflitration of the bone marrow.

Aged↗

PubMed1991

Psittacosis and arthritis.

Recent findings justify the opinion that Chlamydia psittaci is the reappearance of a forgotten pathogen. The clinical manifestation and the course of psittacosis are extremely variable, whereas the clinical spectrum of the infection with the different strains of C. psittaci is not known. Reactive arthritis during the course of psittacosis has been rarely described in humans. However, it has been stated that C. psittaci could be added to the list of infectious agents able to induce reactive arthritis. We describe a patient who presented with clinical signs consistent with reactive arthritis during the course of psittacosis, and we emphasize the good therapeutical results with ceftriaxone in the treatment of psittacosis.

Ankle Joint↗

PubMed1982

Kinetics of heat damaged autologous red blood cells. Mechanism of clearance from blood.

The kinetics of radiolabelled heat damaged red cell (HDRBC) distribution have been studied in humans using a gamma camera, and compared with the kinetics of other blood cells. Liver uptake of 111In labelled HDRBC was completed within about 10 min of injection; splenic uptake was biphasic with a half time of about 5 min over the first 20 min following injection, and a later half time much longer than this. Activity initially present in the lung fields cleared within 24 h. The rate constants of liver uptake of 99mTc labelled HDRBC and of 111In labelled platelets were very similar; the rate constants of splenic uptake of these 2 particles were also very similar up to about 20 min following injection when the splenic platelet levels became constant and the HDRBC level continued to slowly rise. Splenic uptake and blood clearance of red cells coated with IgG (IgG-RBC), in contrast to HDRBC, were monoexponential. It was concluded that: (1) the blood clearance of HDRBC was due to pooling within, and to irreversible extraction by, the spleen; (2) liver uptake of HDRBC, which was irreversible, was completed within 10 min of injection; (3) IgG-RBC clearance was due to irreversible extraction by the spleen; (4) HDRBC uptake in the lung was unrelated to reticuloendothelial function, and represented prolonged transit through the lung microvasculature.

Blood Platelets↗

PubMed1982

Elution of 111Indium from reticuloendothelial cells.

Measurement of isotope accumulation in an organ is often used to assess that organ's removal of blood cells labelled with the isotope. This technique is only valid if the isotope does not elute from the organ. Elution of 111In from the liver and spleen has been investigated in 14 subjects following intravenous injection of heat-damaged erythrocytes labelled with 111In. The elution rate from the spleen was found to be low, about 2% of the initial activity per day. The liver accumulated activity with respect to its initial uptake at a rate of about 5% per day. Bone marrow was not visualised except in two patients in whom it was identifiable in the initial scan.

Erythrocytes↗

PubMed1981

Analysis of heat-damaged erythrocyte clearance curves.

The rate of clearance from the blood of heat-damaged erythrocytes (HDE) is used routinely as a quantitative assessment of splenic function. The time taken for the value at 3 min to fall by 50% (t0.5)is usually taken as the index of function. The clearance of HDE is dependent on three processes: splenic blood flow, splenic HDE extraction ratio and intrasplenic transit time of "unextracted' HDE, returning to the circulation. Exponential analysis of the clearance curve can resolve these three functions. Simple methods of analysis, however, such as t0.5, which are applied directly to the curve, may be weighted in favour of any one of them. In this paper, a large number of clearance curves have been analysed and the components of splenic function resolved. The t0.5, the percentage fall in HDE between 8 and 28 min (C20), the rate constant at 8 min (K8) and the rate constant of the tail of the curve (alpha 2) have been correlated with these components. K8 showed a close correlation with splenic blood flow, and alpha 2 with the rate of HDE phagocytosis. In general, the correlation between the various components of splenic function was better with C20 than with t0.5. This is explained predominantly by the fact that the t0.5 includes liver clearance. The t0.5 should therefore be used with caution as an estimate of splenic function, which can be usefully assessed by applying alternative simple methods of analysis described.

Erythrocytes↗

PubMed1981

Measurement of splenic function in humans using heat damaged autologous red blood cells.

Functional hyposplenism, a clinical entity which has only recently been recognised, is usually assessed quantitatively by the rate of clearance of radiolabelled heat damaged erythrocytes (HDE) from the circulation. Based on recent observations on the kinetics of HDE, we have developed a 3 compartmental model of HDE distribution between the spleen and blood, and calculated, in a large series of clearance curves, splenic blood flow, HDE intrasplenic transit time and splenic HDE extraction ratio. Transit time (about 15 min) was of the same order as platelet transit time and extraction ratio (about 35%) was similar to that recorded in animals. Thr relationships between blood flow, transit time and extraction ratio provided evidence in support of 2 separate functional compartments, of which only one was engaged in phagocytosis, present within the spleen.

Erythrocytes↗

PubMed1981

Spleen function and platelet kinetics.

In patients suffering from various platelet abnormalities, quantitative scanning after injection of indium-111 (111In) labelled platelets showed three different patterns of platelet destruction and distribution. In patients with a normal platelet life span but with evidence of increased splenic pooling, the spleen tended to be the main site of destruction. In patients with a moderately reduced platelet life span, the distribution of destruction in the system and variable destruction in the marrow. However, because of its rapidity this destruction was difficult to quantify, and it was difficult in these cases to distinguish reliably between spleen pool, sequestration, and destruction. Destruction of platelets on the liver appeared to be unimportant in all three groups. 111In, because of its physical characteristics, is preferable to chromium-51 as a platelet label in the assessment of abnormal platelet kinetics.

Adolescent↗

PubMed1980

Use of 111Indium-labeled platelets to measure spleen function.

The distribution of 111In-labelled platelets following intravenous bolus injection has been studied using a gamma camera and computer system. Liver uptake, which accounted for about 10% of the dose, was completed between 6 and 10 min after injection. Blood pool and splenic 111In, which accounted for the remainder of the dose, reached constant levels simultaneously about 20 min after injection. The kinetics of splenic uptake are consistent with a two compartmental model in which circulating and splenic platelets are in dynamic equilibrium with each other. From analysis of the kinetics, splenic blood flow and the mean transit time of platelets through the spleen have been calculated in normal subjects and in patients with haematological disorders. Blood flow, which was about 200 ml per min in normals, tended to increase with increasing spleen size. Transit time was not dependent on spleen size; it was about 10 min in all but one of the subjects.

Blood Platelets↗

PubMed1980

Radionuclide distribution following injection of 111Indium-labelled platelets.

Platelets labelled with 111In displayed similar survival curves after incubation with 111In-oxine in plasma, plasma-saline and dextrose saline media. The use of autologous red cells to cushion platelets during high-speed centrifugation facilitated platelet resuspension without greatly affecting the duration of the labelling procedure. Quantitative scanning after reinjection of labelled platelets in haematologically normal subjects showed that, initially, splenic indium amounted to about 35% of the injected dose and hepatic indium about 12%; these levels rose only slightly over the subsequent duration of the platelet life span. Subtraction of the signal from indium in platelets thought to be normally pooled within the spleen from the total indium signal gave splenic indium uptake curves which reflected splenic platelet destruction. Initially, the sum of indium levels in spleen, liver and blood equalled 100% of the dose. Thereafter, the sum fell progressively at a rate thought to be approximately equal to the rate of bone marrow uptake.

Blood Platelets↗