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Biomedical subjects

A Iolascon

Publications and source records attributed to A Iolascon.

At least 127 records · Page 7Linked to original sources
PubMed1991

Analysis of N-ras gene mutations in medulloblastomas by polymerase chain reaction and oligonucleotide probes in formalin-fixed, paraffin-embedded tissues.

Precise data on the incidence of transforming ras oncogenes in pediatric tumors and the correlations with the histopathological properties of the tumors are very limited. Additionally the presence of ras activation in medulloblastomas has not been investigated so far. Using a combination of techniques including in vitro gene amplification by polymerase chain reaction (PCR) and detection of single base mutations by sequence-specific oligonucleotides we studied N-ras activation (mutations at codon 12, 13, and 61) in 32 medulloblastomas. DNA was isolated from 20 microns sections of formalin-fixed paraffin-embedded tissue. Mutations were found in 3 out of 32 examined medulloblastomas. In all cases only mutations of codon 61 were found: two of three mutations were C to A mutations at position 1 of the codon 61 (leading to a substitution of a glutamine residue for a lysine) and one was A to T mutation at position 3 in the same codon (glutamine-histidine). Our results indicate 10% incidence N-ras mutation in medulloblastoma, higher than in other CNS tumors studied so far. The main advantages of the procedure described are its greatly improved sensitivity, the increased speed with which tumor samples can be analyzed, and the possibility of using paraffin-embedded sections to analyze various rare tumors in retrospect.

Adolescent↗
PubMed1991

Ankyrin deficiency in dominant hereditary spherocytosis: report of three cases.

We describe three Italian subjects from two unrelated families affected with isolated hereditary spherocytosis (HS) without other clinical abnormalities, associated with partial spectrin and ankyrin deficiency. In both families the propositus has normal biological parents, and thus appears to be the result of a new mutation; in one of them the disease is further transmitted in an autosomal dominant fashion. Cytogenetic analysis of the latter family excluded abnormalities of the short arm of chromosome 8. We speculate that in both kindreds ankyrin deficiency is the primary defect related to ankyrin gene mutation. Several pieces of evidence suggest that ankyrin deficiency is probably the most common molecular defect in HS. It is inherited in a, dominant manner and its clinical and biochemical expression is heterogenous.

Adolescent↗
PubMed1985

Genetic heterogeneity at the glucose-6-phosphate dehydrogenase locus in southern Italy: a study on the population of Naples.

Glucose-6-phosphate dehydrogenase (G6PD) electrophoretic phenotype was determined in red cells from 979 male subjects born in Naples (Southern Italy). In 0.7% of the cases no activity could be detected in haemolysates, while in 1.3% of the cases G6PD activity was approximately 20% of normal and electrophoretic mobility was altered. Moreover in two subjects a G6PD with altered mobility and normal activity was shown. G6PD was characterized in 10 subjects with variant phenotype. We conclude that the G6PD(-) phenotype in the population of Naples consists of at least six different G6PD variants associated with mild deficiency and at least one, G6PD Mediterranean, associated with severe deficiency.

Erythrocytes↗
PubMed1985

Erythrocytic zinc content during childhood.

The aim of the study was to investigate developmental changes of erythrocytic zinc occurring during childhood. We have studied 166 healthy children (36 newborn infants, 34 infants aged 1-12 months, 15 aged 1-2 years, 15 children aged 2-4 years, 11 aged 4-6 years and 55 aged 6-12 years); 20 adults were also examined. Mean and standard deviations of the erythrocytic zinc content (pg/10(6) RBC) in the serial samples from children and adults were as follows: newborn infants: 507 +/- 197; infants aged 1-3 months: 521 +/- 117; aged 4-5 months: 559 +/- 203; aged 6-7 months: 574 +/- 251; aged 8-12 months: 771 +/- 243; aged 1-2 years: 802 +/- 204; aged 2-4 years: 963 +/- 278; aged 4-6 years 1,179 +/- 284; aged 6-12 years: 1,256 +/- 186; adults: 1,482 +/- 390. The results have shown that RBC zinc levels increase during the first years of life. Up to the 4th year it is still lower than that observed in adults, although after that age, the mean values do not vary significantly from those observed in adults.

Adult↗
PubMed1983

Increased methyl esterification of membrane proteins in aged red-blood cells. Preferential esterification of ankyrin and band-4.1 cytoskeletal proteins.

The enzymatic carboxyl methyl esterification of erythrocyte membrane proteins has been investigated in three different age-related fractions of human erythrocytes. When erythrocytes of different mean age, separated by density gradient centrifugation, were incubated under physiological conditions (pH 7.4, 37 degrees C) in the presence of L-[methyl-3H]methionine, the precursor in vivo of the methyl donor S-adenosylmethionine, a fourfold increase in membrane-protein carboxyl methylation was observed in the oldest cells compared with the youngest ones. The identification of methylated species, based on comigration of radioactivity with proteins stained with Coomassie blue, analyzed by sodium dodecyl sulfate/polyacrylamide gel electrophoresis, shows, in all cell fractions, a pattern similar to that reported for unfractionated erythrocytes. However in the membrane of the oldest erythrocytes the increase in methylation of the cytoskeletal proteins, bands 2.1 and 4.1, appears to be significantly more marked compared with that observed in the other methylated polypeptides. Furthermore the turnover rate of incorporated [3H]methyl groups in the membrane proteins of the oldest cells markedly increases during cell ageing. Particularly in band 4.1 the age-related increase in methyl esterification is accompanied by a significant reduction of the half-life of methyl esters. The activity of cytoplasmic protein methylase II does not change during cell ageing, while the isolated ghosts from erythrocytes of different age show an age-related increased ability to act as methyl-accepting substrates, when incubated in presence of purified protein methylase II and methyl-labelled S-adenosylmethionine, therefore the relevance of membrane structure in determining membrane protein methylation levels can be postulated. Finally the possible correlation of this posttranslational protein modification with erythrocyte ageing is discussed.

Adult↗