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Biomedical subjects

G Modiano

Publications and source records attributed to G Modiano.

At least 37 records · Page 2Linked to original sources
PubMed1986

Colour blindness distribution in the male population of Rome.

A total of 3,285 young males selected at random from the school population of Rome have been administered the Ishihara plates for colour blindness. Those who failed to read all plates correctly were further administered Farnsworth's Panel D-15 and the diagnoses of colour blindness were made by an ophthalmologist and cross checked. A total of 201 subjects were found to be colour-blind, allowing a gene frequency estimate of 0.061 +/- 0.004. This is the first reliable estimate for the Italian population and appears to be lower than for other Caucasoid populations. The gene frequency of colour blindness is known to increase from 0.02-0.04 in 'primitive' populations to 0.07-0.09 in Caucasoid populations, possibly as a result of a selection relaxation.

Adolescent↗
PubMed1983

The quantitative expression of delta and beta human globin genes is controlled by both 5' and 3' untranslated regions.

The basis for the wide difference in the amounts of haemoglobins A and A2 found in normal human blood is not yet known. By analysing existing data on the levels of haemoglobins Lepore, anti-Lepore, and the recently discovered haemoglobin Parchman, resulting from a double cross-over within the delta-beta region, it is shown that regulation of the expression of these genes must take place at sites located within both their 5' and 3' untranslated regions.

Gene Expression Regulation↗
PubMed1981

Nonrandom patterns of codon usage and of nucleotide substitutions in human alpha- and beta-globin genes: an evolutionary strategy reducing the rate of mutations with drastic effects?

Nucleotide substitutions within a structural gene can cause two principal "drastic" phenotypic effects at the protein level: translatable leads to untranslatable and nonpolar hydrophobic in equilibrium hydrophilic amino acid substitutions. The sequence of nucleotides in the structural human alpha- and beta-globin genes and their variants were examined to determine whether codon usage, patterns of nucleotide substitutions, or both, reduced the relative and absolute rates of these unfavorable mutations. Based on translation of abnormal hemoglobins, it is likely that all 61 nontermination codons are potentially translatable, though only 47 are normally used. Moreover, codons that can mutate to a termination codon are never used whenever the corresponding amino acid is specified also by triplets that cannot mutate to termination by a single-step mutation. Thus, the number of opportunities to mutate to an untranslatable codon is reduced to the minimum compatible with the amino acid composition of these chains. The relative rates of U in equilibrium non-U substitutions were much lower than those of other substitutions. Because U residues must be involved in most termination mutations and in all nonpolar hydrophobic in equilibrium hydrophilic amino acid substitutions, there is a considerable reduction of mutational events, causing drastic phenotypic effects. These findings are likely to be the end result of evolutionary selection by yet unknown mechanisms.

Base Sequence↗
PubMed1981

Researches on the biology of Himalayan populations.

This long term project is aimed to study the following points: 1. Evolutionary adaptation to high altitude. 2. Population genetics of high altitude populations and 3. Mechanisms of resistance to malaria in some of these. The study suggests that the Sherpa of Nepal and the Quechua of Peru, living at altitude about 4000m, may have adapted to low oxygen pressure. The results of biochemical marker studies show that the Himalayan populations may remain genetically separated even when sharing the same village. Studies relating to resistance to falciparum malaria indicate that the immunity, conferred on the Tharu against malaria, may not involve erythrocytes exclusively.

ABO Blood-Group System↗
PubMed1980

Population genetics of red cell enzymes in Pygmies: a conclusive account.

In the course of a long-term research project, three groups of Pygmies and some non-Pygmy Central Africans have been examined for the following red cell enzyme markers: ACP, PGM1, PGM2, PEPA, PEPB, and PEPC, AK, ADA, and PHI. Several other red cell enzymes (ESD, CA1 and CA2, GPT, GLO, and DIA1) have been studied in only some of these groups. This paper reports all the information we obtained, including what we have already published. The following conclusions can be drawn from the whole body of data: (1) Gene patterns of Pygmies are those typical of other Africans (e.g.: lack of ADA2 and AK2 genes, low GPT2 gene frequency, polymorphism of the CA2 locus, and presence at polymorphic frequencies of PEPA2 allele. (2) Superimposed on this African genetic makeup, a number of Pygmy characters were identified, namely, a private polymorphism for the PGM26 Pygmy allele and possibly one for the PEPC2 allele, and particularly high ACPR and low PGM12 gene frequencies. (3) Some markers, especially PGM1 and ACP, turned out also to discriminate efficiently among different groups of Pygmies.

Black People↗
PubMed1979

Genetic heterogeneity of "normal" human erythrocyte glucose-6-phosphate dehydrogenase: an isoelectrophoretic polymorphism.

Quantitative determination of glucose-6-phosphate dehydrogenase (G6PD; D-glucose-6-phosphate: NADP+ 1-oxidoreductase, EC 1.1.1.49) activity was carried out in 214 male Nigerian children of 84 mothers with known Gd genotype. The relative intrasibship difference in G6PD activity (normalized to the lowest value within the sibship) was below 0.18 in all cases but one when the children were known to have the same Gd+ allele (identical by descent); whereas it was higher than 0.18 in 18 out of 33 sibships in which children might have had either of the two maternal (electrophoretically identical) Gd+ alleles. G6PD from 10 (8 G6PD B and 2 G6PD A) children belonging to four of the sibships possessing high quantitative variation in G6PD activity was partially purified and extensively characterized. The 8 G6PD type B samples fell unambiguously into two classes on the basis of Km values for glucose 6-phosphate (determined at variuos pH values), and KCl gradient elution from DEAE-Sephadex columns. The two types of G6PD B were resolved from an artificial mixture on a DEAE-Sephacel column. The two G6PD type A samples were also different from each other by the same criteria. We conclude that "normal" G6PD is genetically heterogeneous and that the structural Gd alleles concerned are all polymorphic in the Nigerian population. In this instance, a human enzyme polymorphism, not associated with enzyme deficiency, is revealed by an approach other than electrophoresis.

Alleles↗
PubMed1977

Comparison of GdA and GdB activities in Nigerians. A study of the variation of the G6PD activity.

We report a comparison between G6PD enzyme activities in lysates from GdA and GdB Nigerian healthy males. We confirm the previously reported higher mean activity of G6PD B. An analysis of the enzyme activity variation has been performed: the relative amount of variation found to be associated with this polymorphism is about 8%. A comparison has been made with other genetic polymorphisms.

Child↗
PubMed1976

Sherpas living permanently at high altitutde: a new pattern of adaptation.

Adaptation of Sherpas to high altitude has been studied and compared with that of Caucasians acclimatized to high altitude. Sherpas living permanently at 4000 m above sea level do not have increased hematological parameters (i.e., red cell number, hematocrit, hemoglobin content, and 2,3-diphosphoglycerate/hemoglobin ratio) and have a higher affinity of blood for oxygen as compared with acclimatized Caucasians. Sherpas permanently living at low altitude, on the contrary, have lower affinity of blood for oxygen than do Caucasians living at comparable altitude and are mildly "anemic,". Various other red cell biochemical parameters (possibly related to adaptation to altitude) have also been studied in the same population. We suggest that Sherpas are genetically better adapted to high altitude than are Amerindians living on the Peruvian highlands, possibly as a consequence of a much more prolonged exposure to such an ecological factor of selection as high altitude.

Adaptation, Physiological↗