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Biomedical subjects

D Loukopoulos

Publications and source records attributed to D Loukopoulos.

At least 127 records · Page 7Linked to original sources
PubMed1980

Haematological aspects of antenatal diagnosis for thalassaemia in Britain.

The results are described of 200 antenatal diagnostic tests for haemoglobinopathies performed on samples of fetal blood obtained during the second trimester of pregnancy. Haemoglobin A synthesis in the fetus was measured by incorporation of tritiated leucine in vitro and separation of the globin chains on CM23 columns. The range of HbA synthesis detected was 3.5-8.0% in normal fetuses, 2.0-5.0% in fetuses with thalassaemia trait, and less than 1.6% in fetuses with thalassaemia major. There were eight cases in which other haemoglobinopathies were diagnosed. 29% of the pregnancies were terminated because thalassaemia major was diagnosed, and 9.5% of the remaining healthy fetuses were lost for obstetric reasons. Follow up has been possible for 96% of the 124 surviving babies and three misdiagnoses have come to light; one false positive (0.5%) and two false negatives (1%). These figures represent a first effort at antenatal diagnosis for haemoglobinopathies and it is likely that they will improve with the passage of time.

Chromatography, Ion Exchange↗
PubMed1980

Proteolysis in thalassemia: studies with protease inhibitors.

Intracellular proteolysis was studied in both thalassemic and normal reticulocytes. The main experiment comprised a short incubation of RBC with [3H] leucine, extensive washings, and further incubation in the presence of cold leucine and protein synthesis inhibitors. In the aliquots removed at various time intervals, the TCA-soluble radioactivity increased in contrast with the TCA-precipitable cpm, which decreased with no exception on prolonged incubation. Results were more pronounced when the initial incubation was carried out in the presence of a valine analog and were markedly inhibited when phenanthroline was added during the second phase of the experiment. Cell-free system gave similar results. "globin" containing analog residues were degraded easier than free alpha- and beta-globin chains; free alpha or beta Hb chains are not proteolysed. Thalassemic and normal reticulocytes did not show any significant differences. It is proposed that the thalassemic RBC contain efficient proteolytic mechanisms up to the end of their maturation, but these prove incapable of proteolysing the excess alpha chains completely. Chemical manipulations aiming to make those chains more digestible constitute another approach to the treatment of thalassemia.

Aminobutyrates↗
PubMed1980

Glycerol-3-phosphate dehydrogenase activity in the red cells of patients with thalassemia.

L-alpha-Glycerol-3-phosphate dehydrogenase (EC 1.1.1.8) has been reported to be absent in the erythrocytes of normal adults, but can be found in those of cord blood and of thalassemia major. The aid of this study was to investigate whether there is any relation between GDH and gamma-chain synthesis. Erythrocyte GDH activity was determined on 118 different blood samples. It was undetectable in normal adult erythrocytes and definitely high in cord blood cells (23.6 UI/10(11) RBC). Considerable GDH activity was also noted in patients with thalassemia major (11.0 IU10(11) RBC) as well as in cases with pronounced reticulocytosis (11.4 IU/10(11) RBC). Red cells from beta-thalassemia heterozygotes exhibited moderate but distinct GDH activity (5.2 IU/10(11) RBC). After fractionation into young and old erythrocyte populations, clearly higher GDH activity was found in the younger cells; however, there was no significant correlation with the reticulocyte count. Presence of reticulocytes alone appears insufficient to explain the values obtained in cord blood and the thalassemias, especially heterozygous. Furthermore, no direct correlation between GDH and fetal hemoglobin (HbF) was obtained in cord and thalassemic erythrocytes.

Adult↗
PubMed1979

Prenatal diagnosis of beta-thalassemia.

Prenatal diagnosis was attempted in 14 fetuses at risk for homozygous beta-thalassemia, gestational age 18-22 weeks. In 4 cases the placenta was entirely anterior, placental aspiration under ultrasonic control only had to be used for fetal blood sampling. In 10 fetuses fetoscopy was used for puncture of a chorionic blood vessel. Diagnoses were based on the rate of in vitro synthesis of beta-globin related to total non-alphaglobin synthesis. With the aid of fetoscopy, nearly pure fetal blood was obtained in general. Placental aspiration resulted in samples which contained a low percentage of fetal and a high percentage of maternal cells. The attempt of fetal blood sampling resulted in fetal loss in two cases. In 2 aspiration cases no diagnosis could be made because the samples were inadequate. In 2 cases the diagnosis was established in spite of low fetal cell content through determination of the specific radioactivity in the placental and pure maternal blood. Until now 6 children have been born in whom prenatal diagnosis had been attempted, none of them has homozygous thalassemia. Present efforts are directed toward improving the safety of fetal blood sampling and the biochemical methods for the diagnosis in placental samples with low fetal cell content. Although the prenatal diagnosis of beta-thalassemia is possible, the procedure has still to be considered experimental.

Female↗
PubMed1979

Rhodotorulic acid--investigation of its potential as an iron-chelating drug.

The use of rhodotorulic acid (RA) as an iron-chelating drug was suggested by experiments in hypertransfused rats in which urinary and fecal iron excretion were significantly enhanced in response to RA. The toxicity of the drug appears to be minimal at a parenteral dose less than 250 mg/kg. An increased excretion of zinc was the only notable side effect of the drug at the doses used. When administered i.v. to humans, RA was only 16% more effective than desferrioxamine (DF). Pharmacokinetic studies showed that RA persisted in the bloodstream of dogs 6 times longer than desferrioxamine after an intravenous injection. Accordingly RA was evaluated as a potential repository drug. While animal experiments were encouraging, human subjects experienced a painful local reaction to RA administered either i.m. or s.c. as a suspension in physiological saline. Accordingly it appears that RA is best looked at as a second line drug, unless a means can be found to obviate local inflammatory reactions.

Adult↗
PubMed1978

Antenatal diagnosis of thalassaemia major.

Haemoglobin synthesis was studied in fetal blood samples obtained at 17 to 20 weeks' gestation in 22 women at risk of carrying a fetus with homozygous beta-thalassaemia. A presumptive diagnosis of homozygous beta-thalassaemia was made in four cases, and the pregnancy was terminated. An inconclusive answer was obtained in one case, and the patient also chose to have her pregnancy terminated. Two fetuses were lost as a result of the procedure. Of the remaining 15 pregnancies, 13 proceeded to term and two to 36 weeks; in each case a normal infant or one heterozygous for beta-thalassaemia was delivered. Current efforts should be directed towards improving the blood sampling technology so that fetal blood sampling can be used widely in those countries where thalassaemia is a major problem.

Abortion, Eugenic↗
PubMed1978

A unique thalassaemic syndrome: homozygous alpha-thalassaemia + homozygous beta-thalassaemia.

The disturbed balance of globin chain synthesis is a major factor in the pathophysiology of the thalassaemic disorders; this concept is strongly supported by the study of a patient displaying an extreme but symmetrical deficit of both major types of chains alpha and beta. The patient had a mild clinical picture but presented a striking hypochromia (MCH 10 pg) with compensatory erythrocytosis (RBC 10(12)/l.). Study of the propositus and his family by haematological, biochemical and biosynthetic techniques indicates that the patient carries two alpha- and two beta-thalassaemia genes resulting in balanced globin chain synthesis; in addition, several members of the family carry two or three abnormal genes. During observation a change in the haematological pattern occurred with a shift towards more intensive beta-chain and away from gamma-chaim synthesis; this appeared with be associated with improvement of his anaemia through more effective erythropoiesis.

Adult↗
PubMed1977

Angio-immunoblastic lymphadenopathy terminating as Hodgkin's disease.

The clinical course of a 33-year-old man with generalized lymphadenopathy bearing all physical, laboratory and histologic characteristics of "angio-immunoblastic lymphadenopathy with dysproteinemia" (AILD) is described. Therapy was without significant benefit and the patient died 22 months after initial diagnosis. At autopsy in addition to the characteristic cellular polymorphism of AILD, numerous Hodgkin's cells and Sternberg-Reed cells were identified in the lymph nodes and spleen. Pleomorphic cellular infiltrates containing an increased number of immunoblasts and some giant cells were found also in the portal spaces of the liver. The evolution of Hodgkin's disease (H.D.) from AILD suggests that the latter may have represented a reaction to the agent which causes H.D..

Abdomen↗
PubMed1976

Role of copper in mitochondrial iron metabolism.

Heme synthesis by copper-deficient cells was investigated to elucidate the nature of the defect in intracellular iron metabolism. Iron uptake from transferrin by copper-deficient reticulocytes was 52% of normal, and the rate of heme synthesis was 33% of normal. Hepatic mitochondria isolated from copper-deficient animals were deficient in cytochrome oxidase activity and failed to synthesize heme from ferric iron (Fe III) and protoporphyrin at the normal rate. The rate of heme synthesis correlated with the cytochrome oxidase activity. Heme synthesis from Fe(III) and protoporphyrin by normal mitochondria was enhanced by succinate and inhibited by malonate, antimycin A, azide, and cyanide. It is proposed that an intact electron transport system is required for the reduction of Fe(III), thereby providing a pool of ferrous iron (Fe II) for protoheme and heme a synthesis.

Animals↗
PubMed1973

Thalassaemia in Cyprus.

Frequencies of the thalassaemias in Cyprus were examined by a survey of hospital inpatients and haematological investigations of adult and newborn population samples. The data indicate that 15% of the Greek and Turkish Cypriots are carriers of beta-thalassaemia genes, while 10% of the population carry alpha-thalassaemia genes. These are the highest frequencies of thalassaemia genes found today in any Caucasian population.

Adult↗