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D Loukopoulos

Publications and source records attributed to D Loukopoulos.

At least 91 records · Page 5Linked to original sources
PubMed1994

Mechanical hemolysis associated with a bioprosthetic mitral valve combined with a calcified aortic valve stenosis.

We report a case of severe mechanical hemolysis occurring 8 years after insertion of a bioprosthetic mitral valve in a patient who also suffered from aortic valve stenosis. It is suggested that the coexistence of two malfunctioning valves may lead to hemolysis via hemodynamic and turbulence alteration and that this condition is more frequent than expected for isolated valve involvement.

Aged↗
PubMed1994

Bacteroides fragilis arthritis in a sickle cell-thalassaemia patient.

Anaerobic arthritis due to Bacteroides fragilis was diagnosed in a 33-year-old patient with prolonged fever suffering from sickle cell/thalassaemia. The causative agent was isolated from blood and purulent synovial fluid from both knee joints. A combination of chloramphenicol plus metronidazole treatment proved effective. Anaerobic arthritis has not previously been described in patients with sickle cell disease, and may reflect the well-known susceptibility of these patients to pathogens.

Adult↗
PubMed1993

Flow-cytometric analysis of reticulocytes in normal cord blood.

We performed precise reticulocyte counts and a reticulocyte maturation study according to ribosomal RNA (rRNA) content, in normal cord blood. For this purpose we analyzed 35 cord blood specimens corresponding to a mean gestational age of 39.2 weeks (range 38-41). In all specimens complete blood counts were performed with the H*1 (Technicon, Bayer) analyzer. Reticulocyte maturation study and counts were conducted by the R-1000 (Sysmex) reticulocyte analyzer. We obtained the following measurements (mean +/- 1 SD): reticulocyte percentage 3.11 +/- 0.75% and reticulocyte absolute count 137.3 +/- 33.3 x 10(9)/l. There was no correlation between the reticulocyte counts and the duration of gestation or the type of labor (normal, forceps assisted or cesarean section). Reticulocyte subpopulations with different rRNA content and maturation were expressed as reticulocytes with high (HFR), median (MFR) and low (LFR) fluorescence of the fluorochrome auramine bound to rRNA. Normal cord values were: HFR% = 13.6 +/- 2.4, MFR% = 22.5 +/- 2.4 and LFR% = 63.9 +/- 4.3. Reference maturation subpopulations were assessed for comparison in 180 samples of healthy adults (90 males and 90 females) and were found HFR% = 1.0 +/- 0.8, MFR% = 9.7 +/- 3.3 and LFR% = 89.2 +/- 3.4. The HFR% and MFR% were significantly higher while LFR% was significantly lower (p < 0.001) in cord compared to adult blood, denoting a shift to more immature reticulocyte forms. The above values are provided as normal reference data of the reticulocyte maturation profile in full-term cord blood.

Adult↗
PubMed1991

Thalassemia: genotypes and phenotypes.

The large degree of phenotypic heterogeneity of thalassemia can now be related to the underlying genomic defects. This information has accumulated rapidly over the last years through the recent advances in molecular technology. The list of main types of thalassemia (alpha or beta) that can be differentiated includes several gene deletions (complete or partial) and point mutations (or very short deletions). These occur within the genes or across the flanking DNA sequences and apparently interfere with the expression of these genes. From a quantitative point of view, the severity of the condition is directly related to the amount of functional globin chain mRNA which is made available to the ribosomes; this may vary from zero (gene deletions, frameshift, non-sense mutations or mutations at the splice-junction nucleotides) to very little (mostly hnRNA processing mutants) or to slightly subnormal (transcriptional mutants, mutations resulting in cryptic site activation or in defective cleavage of the poly-A tail). A few hyper-unstable globin chains also produce a thalassemic phenotype. This pattern is straightforward in the alpha-thalassemias. In the beta-thalassemias, the decreased beta-chain synthesis reflects the available mRNA, but the phenotypic expression depends also on the ability of the patient to reactivate gamma-chain synthesis and complement the red cell content with hemoglobin F.

Genotype↗
PubMed1991

Reticulocyte counting in thalassemic and other conditions with the R-1000 Sysmex analyzer.

Precise reticulocyte counts are difficult to obtain by the manual method when their percentage in the blood is low or normal. In these instances, rapid reticulocyte counting by flow cytometry appears to offer more accuracy and precision. The purpose of this study was to establish reticulocyte counts in heterozygous beta-thalassemia for reference purposes and to evaluate the performance of the recently introduced apparatus R-1000 (Sysmex) in the very heterogeneous thalassemic and sickle-cell syndromes. We studied a total of 364 samples; 102 heterozygous beta-thalassemia carriers, 180 normal matched controls, 36 patients with thalassemia major or intermedia, and 46 patients with various sickle-cell syndromes. Reticulocyte counts (both as percentage and as total number) were higher in heterozygous beta-thalassemia than in normal controls (p less than 0.001) and showed an inverse correlation with the respective hemoglobin values (p less than 0.001). These results confirm the proposed slightly increased erythropoietic activity in heterozygous beta-thalassemia carriers. A drawback of the technique is that the reticulocyte-platelet discrimination error is signaled frequently in all conditions displaying a marked red cell heterogeneity, especially when these are associated with high reticulocyte numbers. This calls probably for readjustment of the corresponding algorithm. In addition, all these conditions show a significantly increased auramine-O mature red-cell nonspecific fluorescence.

Anemia, Sickle Cell↗
PubMed1991

A comparison of sickle cell syndromes in northern Greece.

Haematological and clinical characteristics have been examined in 30 patients with homozygous sickle cell (SS) disease, 28 with sickle cell-beta zero thalassaemia, and 21 with sickle cell-beta+ thalassaemia. The latter could be divided into three groups on their molecular basis and HbA levels, four subjects with an IVS-2 nt 745 mutation having 3-6% HbA (designated S beta+ thalassaemia type I), 14 subjects with an IVS-1 nt 110 mutation having 8-15% HbA (designated S beta+ thalassaemia type II), and three subjects with an IVS-1 nt 6 mutation having 20-25% HbA (designated S beta+ thalassaemia type III). Comparisons were conducted between SS disease, S beta zero thalassaemia, and S beta+ thalassaemia type II. Compared to SS disease, both thalassaemia syndromes had higher HbA2 levels and red cell counts and lower mean cell haemoglobin content (MCHC), mean cell volume (MCV) and MCH, and S beta zero thalassaemia had higher HbF and reticulocyte counts. Compared to S beta zero thalassaemia, S beta+ thalassaemia had a higher haemoglobin and MCHC. Clinically, persistence of splenomegaly was more common in S beta zero and S beta+ thalassaemia type II compared to SS disease. Few significant differences occurred between SS disease, S beta zero and S beta+ thalassaemia type II in Northern Greece suggesting that the 8-15% HbA in the latter condition was insufficient to modify the clinical course.

Adolescent↗
PubMed1991

The origin of the sickle mutation in Greece; evidence from beta S globin gene cluster polymorphisms.

Study of the Hpa I polymorphism 3' to the beta-globin gene in the Greek population revealed absence of the site in 238 beta S chromosomes, in contrast to a much larger sample of chromosomes carrying the beta A gene, where this site was consistently positive. Subsequent haplotype analysis of the beta-globin gene cluster in 82 beta S chromosomes demonstrated that 79 (96%) belonged to haplotype #19, while the three exceptions (all Hpa I negative) could be explained by a delta-beta recombination event. Haplotype #19 was never encountered in a parallel study of the 83 beta A chromosomes. Comparison of the above results with similar surveys in other parts of the world and consideration of various historical events suggest that the beta S mutation was introduced into Greece over the last few centuries by the Saracen raids and/or by settlements of North African slaves brought in by the Arabs, Franks, Venetians, or Ottoman Turks, who have occupied the country over the last millennium.

Africa, Northern↗
PubMed1991

A C----G mutation at nt position 6 3' to the terminating codon may be the cause of a silent beta-thalassemia.

We describe the hematological and clinical data for a young Greek patient with beta-thalassemia intermedia and for several members of her family. The patient had inherited the common IVS-I-1 (G----A) mutation from her mother, while the second beta-globin gene had a C----G mutation at position 6 3' to the terminating codon (term. + 6). Her father and three additional relatives with a heterozygosity for this newly discovered mutation had no hematological abnormalities, normal Hb A2 values, and a nearly normal in vitro chain synthesis ratio. Analyses of nearly 500 additional beta-thalassemia and normal chromosomes failed to detect this mutation which eliminates it as a common polymorphism. Although our findings may indicate a rare polymorphism, the probability that it represents the cause of diminished beta chain synthesis is very high indeed. We suggest that the C----G mutation in this untranslated region of the beta-globin gene causes a slight decrease in the stability of the mRNA which becomes clinically important only in situations when beta chain synthesis in trans is eliminated.

Base Sequence↗
PubMed1990

Comparison of homozygous sickle cell disease in northern Greece and Jamaica.

The clinical and haematological features of homozygous sickle cell (SS) disease were compared in 30 Greek and 310 Jamacian patients. Deletional alpha-thalassaemia, which modifies SS disease, is rare among Greek patients, so only Jamacian patients with four alpha-globin genes were included in the control group. Greek patients had higher total haemoglobin concentration and red cell counts, and lower mean cell haemoglobin concentration (MCHC) and reticulocyte counts. They also had a more normal body build and more adults had persistent splenomegaly. Fewer had a history of leg ulceration or priapism but more reported acute chest syndrome. The comparatively mild disease in Greek patients is consistent with less haemolysis and sickling and therefore less bone marrow expansion. In the absence of amelioriating factors such as high HbF concentration or alpha-thalassaemia, these findings may be explained by the low MCHC.

Adolescent↗
PubMed1990

Cystic fibrosis in Greece: typing with DNA probes and identification of the common molecular defect.

The relative frequency of the delta F508 mutation in the Greek population is 54.1%; this is similar to that reported in other Southern European populations and contrasts with the considerably higher frequencies encountered in Northern Europe and North America. The low frequency is in agreement with the linkage disequilibrium already reported between cystic fibrosis and haplotype B in this country. In contrast to the common association of pancreatic insufficiency with the homozygous delta F508 genotype, the present study revealed two homozygous children with no evidence of pancreatic failure.

Chromosome Deletion↗
PubMed1989

Frameshift codon 5 [Fsc-5 (-CT)] thalassemia; a novel mutation detected in a Greek patient.

Sequence analysis and dot-blot hybridization of DNA from a Greek patient with a transfusion dependent thalassemia revealed the combination of a beta IVS-I-1 G----A mutation (beta(0) -thalassemia) and a hitherto undescribed frameshift mutation; the latter concerns the absence of a CT dinucleotide from codon 5 and results in a termination signal at the new codon 21 (also a beta (0)-thalassemia).

Adolescent↗
PubMed1989

Hemoglobin Köln occurring in association with a beta zero thalassemia: hematologic and functional consequences.

Hemoglobin (Hb) Köln-beta zero thalassemia compound heterozygosity was discovered in a young Greek patient. This gave us the unique opportunity for studying the functional properties of this unstable high-oxygen affinity hemoglobin variant in red cells containing almost pure Hb Köln. The red cells of the proposita exhibit morphological alterations and hematologic indices corresponding to the presence of an unstable Hb and beta thalassemia. Globin chain synthesis confirmed the association with a beta zero thalassemia gene. Oxygen-binding curves for these cells were biphasic, indicating the presence of both heme-saturated and of approximately 20% of non-cooperative Hb Köln. The major component exhibits an increased oxygen affinity, reduced cooperativeness, and normal alkaline Bohr effect. The 35-year-old proposita is active, has not been splenectomized, and has not been transfused in several years.

Adult↗