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Biomedical subjects

L Tentori

Publications and source records attributed to L Tentori.

At least 73 records · Page 4Linked to original sources
PubMed1980

Post-translational control of human hemoglobin synthesis: the role of the differential affinity between globin chains in the control of mutated globin gene expression.

The interactions between beta-thalassemia and the human hemoglobin (Hb) alpha-chain variants, Hb Hasharon, Hb O Idonesia and Hb J Paris, and between alpha-thalassemia and the beta-chain variants, Hb S, Hb C and Hb G San José, which are characterized by preferential decrease of the abnormal Hb level in peripheral bloods, have been studied. Both biosynthesis studies in reticulocytes and determination of the relative affinity of abnormal chains for normal complementary chains by in vivo recombination experiments, involving globin chains previously isolated in their native form, have been carried out in order to provide insights on the molecular events following the synthesis of the mutant chains under conditions of complementary chain deficiency. Furthermore, we have measured the relative affinity for complementary chain of beta D Los Angeles- and alpha J Rovigo-chains, the level of which does not decay in thalassemic carriers, and of alpha Legnano- and beta Osu Christiansborg-chains, which have not yet been observed in association with thalassemias. Our experiments indicated that the differential affinity for beta-chains is not always the major post-translational control mechanism which regulates the level of certain alpha-chain variants in beta-thalassemic heterozygotes, and that preferential removal of abnormal chains by proteolytic enzymes is likely to play an important role in most cases. On the other hand, the low affinity of certain variant beta-chains for alpha-chains may offer an explanation for the low level of certain beta-chain variants in peripheral blood of non-thalassemic carriers, as well as to their decrease under conditions of relative alpha-chain deficiency (alpha-thalassemias).

Globins↗
PubMed1980

A new human hemoglobin variant: Hb BARI (alpha 2 45 (CD3) His leads to Gln beta 2).

An alpha-chain variant hemoglobin was found in the hemolysate of a 21-year-old healthy male living in Bari (Puglia, Italy). Structural studies demonstrated a previously unreported amino acid substitution, alpha 2 45 (CD3) His leads to Gln beta 2, involving a distal heme contact. The new variant has been named Hb Bari. Its electrophoretic behavior was the same as for Hb A; it was stable to both isopropanol and heat denaturation and exhibited normal functional properties, with respect to whole blood and stripped hemolysate studies. The level of Hb Bari was about 20% in the observed carrier. No relative was available for further investigations.

1-Propanol↗
PubMed1980

Hemoglobin Legnano (alpha 2 141 (HC3) Arg leads to Leu beta2) a new high oxygen affinity variant. Functional and structural studies.

Hb Legnano (alpha 2 141 (HC3) Arg leads to Leu beta 2) is an abnormal hemoglobin, for which preliminary structural and functional studies demonstrated an amino acid substitution (Arg leads to Leu) in the alpha-C-terminus. This substitution modifies the functional properties observed in whole blood as well as in red blood cells, as reported in this paper. On the basis of its pI, previously determined by analytical isoelectric focusing (IEF), Hb Legnano was purified on a preparative IEF slab. The purified fraction was subjected to functional ultracentrifugal studies under various conditions of pH and salt concentration. The findings are compared with those for Hb Suresnes (alpha 2 141 (HC3) Arg leads His beta2) and Hb-CPB, a normal hemoglobin in which the C-terminal alpha 141 Arg has been cleaved by carboxypeptidase B. Hb Legnano, like the other hemoglobins considered, shows an increased P50, a decreased Hill's "n" values and a decreased Bohr effect that are partially restored in presence of organic phosphates. The presence of inorganic ions decreases the Bohr effect and enhances the dissociation into dimers, as observed in Hb-CPB. The dissociation of hemoglobin in carboxy form in ultracentrifugal studies and the different slope of Hill's "n" value as a function of pH are presumably due to presence of Leu, which probably modifies the stereochemistry of the variant.

Amino Acids↗
PubMed1980

Hemoglobin Hasharon [alpha 247 (CD5)Asp leads to His beta 2] linked to alpha-Thalassemia in northern Italian carriers. Hematological and biosynthetic studies.

This report is concerned with the evaluation of hematological parameters and of both relative (%) and absolute (mean pg/cell) quantities of the abnormal Hemoglobin (Hb) Hasharon in 53 heterozygous carriers and 7 double heterozygotes for Hb Hasharon and beta-thalassemia from 43 apparently unrelated families living in the province of Rovigo (northern Italy). Biosynthetic studies are also reported. The data strongly suggest the presence of an alpha-thalassemia-2 determinant closely linked to the alpha Hasharon-chain locus. Selective advantage of heterozygotes carrying such alpha-haplotype would explain the relatively high frequency of Hb Hasharon (0.23%) in northeastern Italy, a past-endemic malaria region. The interaction between Hb Hasharon and beta-thalassemia results in preferential decrease of the abnormal Hb level.

Blood Protein Electrophoresis↗
PubMed1979

A new abnormal human hemoglobin: Hb Prato (alpha 2 31 (B12) Arg leads to Ser beta 2).

An abnormal human hemoglobin was found in a hemolysate from a 5-year-old healthy child living in Prato (Tuscany, Italy). Strutctural studies demonstrated a previously unreported amino acid substitution, alpha 31 (B12) Arg leads to Ser (this is an alpha 1 beta 1 contact). The new variant has been named Hb Prato. It was unstable in isopropanol and heat-denaturation tests, but has normal functional properties, with respect to whole blood studies. Family studies indicated that the variant had been inherited from the mother, a 39-year-old woman of Sicilian extraction. Hb Prato occurs at 20 and 28% in hemolysates from the boy and woman, respectively.

Adolescent↗
PubMed1979

Hemoglobin G San José [beta 2 7 (A4) Glu to Gly alpha 2], beta thalassemia, and alpha thalassemia in a Sicilian family.

A 3-year-old child of Sicilian origin was found to have a severe form of Cooley's anemia. Investigations were extended to other members of her family. In three, a rare beta-chain structural Hb variant, Hb G San José [beta 7 (A4) Glu to Gly], was observed: in the father of the porposita heterozygosity for the abnormal Hb was found to be coexistent with beta o thalassemia; two sisters had lowered MCV and MCH values and levels of the abnormal Hb significantly lower than in other heterozygotes for Hb G San José. The alpha-chain/total beta-chain synthesis ratios suggest an alpha-thalassemic-like effect. Their mother had lowered MCV and MCH values, an Hb A2 level in the upper limit of the normal range, and a balanced alpha-chain/beta-chain synthesis ratio. Therefore, the possibility of coexistence of an alpha thalassemia trait with a beta thalassemia trait in the mother of the proposita and with Hb G San José heterozygosity in the two sisters who had lowered levels of abnormal Hb is discussed.

Child, Preschool↗
PubMed1979

Haemoglobin Lepore trait: haematological and structural studies on the Italian population.

Haematological data on 59 heterozygotes for haemoglobin (Hb) Lepore and 10 double heterozygotes for Hb Lepore and beta thalassaemia from 36 Italian families are reported. The red cell indices are defined and compared with those of groups of non-thalassaemic and beta thalassaemic subjects of comparable number, age and sex distribution. The relative level of each haemoglobin fraction and the absolute production of single polypeptide chains are calculated in order to compare the expression of the non-alpha chain genes in Hb Lepore trait and beta thalassaemia. Structural studies demonstrate that the haemoglobin Lepore is of the Boston type (delta 87 beta 116) in all subjects, confirming that this type of fusion variant is probably the only one which occurs in Mediterranean populations. The distribution and incidence of the Lepore haemoglobinopathy are discussed.

Adult↗
PubMed1979

Occurrence of haemoglobin Norfolk (alpha2 57 (E6) Gly leads to Asp beta2) at the level of 33% in an Italian family from Calabria.

An abnormal, fast-moving haemoglobin was observed in 5 healthy subjects of a family from Calabria (southern Italy). In all these carriers the abnormal haemoglobin, which structural studies identified as Hb Norfolk (alpha2 57 (E6) Gly leads to Asp beta2) [4], occurs at a level averaging 33% of the total haemoglobin. Biosynthetic studies showed no evidence for unbalance of the globin chain synthetic ratio. In order to account for the observed percentages of Hb Norfolk, current concepts about the alpha-globin chain genetic system are reviewed, and different genic arrangements which would be in agreement with the experimental findings are discussed.

Adolescent↗
PubMed1979

Studies on a family with Hb J Calabria (alpha 2 beta 2 64 (E8) Gly replaced by Asp).

Hb J Calabria is a fast moving hemoglobin variant which was found in an Italian family by Vecchio et al (1), and in a French family by Blouquit et al. who studied its functional properties (2). The original family described by Vecchio et al. in which both Hb J Calabria and beta-thalassemia were present has been reexamined and is the subject of the present study. Hematological and clinical features of the carriers are described. The heterozygous carriers of Hb J Calabria showed only mild variable subclinical anemia and levels of the abnormal hemoglobin ranging from about 33 to 42%. The Hb J Calabria/beta-thalassemia double heterozygote showed a moderate chronic hemolytic anemia with alterations of the RBC indices and morphology in addition to splenomegaly. The relationship between structural abnormality, functional properties and clinical expression of Hb J Calabria is discussed.

Aged↗