Linkage disequilibrium for two X-linked genes in Sardinia and its bearing on the statistical mapping of the human X chromosome

The distribution of four X-linked mutants (G6PD, Deutan, Protan and Xg) among lowland and once highly malarial populations of Sardinia discloses a clear-cut example of linkage disequiligrium between two of them (G6PD and Protan). In the same populations the distribution of G6PD-deficiency versus colorblindness of the Deutan type and the Xg blood-group is not significantly different from that expected at equilibrium. These data suggest indirectly that the loci for G6PD and Protan may be nearer to one another than those for G6PD and Deutan.

Synthesis and chromatographic properties of selenazolidine-4-carboxylic acid (selenaproline)

Details are reported for the synthesis of DL-selenazolidine-4-carboxylic acid starting from DL-selenocystine and formaldehyde. Some chemical reactions and the paper and ion-exchange chromatographic behaviour of selenazolidine carboxylic acid in comparison with thiazolidine-4-carboxylic acid are described.

Chromatographic separation of selenohypotaurine, selenotaurine, selenohomohypotaurine and selenohomotaurine

By either paper or ion-exchange chromatography the two seleninic compounds selenohypotaurine and selenohomohypotaurine, and the two selenonic compounds selenotaurine and selenohomotaurine may be all separated from each other. On paper chromatography seleninic derivatives may be separated from the corresponding sulphinic compounds, while selenonic compounds show RF values similar to those of the corresponding sulphonic derivatives. These two latter types of compounds may be differentiated, however, since selenonic compounds liberate iodine from HI, while sulphonic compounds do not. Also by automated ion-exchange chromatography seleninic derivatives are well separated from the analogous sulphinic compounds, while selenonic compounds are eluted together with the corresponding sulphonic compounds.

Hair root versus red cell individual phenotype in Sardinian heterozygotes for G6PD deficiency (Mediterranean type)

G6PD activity was assayed in 20 Sardinian heterozygotes for G6PD deficiency and related to that of LDH and MDH. One of these heterozygotes showed a deficient phenotype in all her follicles, while the remaining 19 had different proportions of deficient, intermediate, and normal follicles. This is in accordance with a previous estimate. Because of the broad fiducial limits at the 5% level and because of some developmental considerations, this value cannot be interpreted as indicative of the number of primordial cells for scalp epidermis at the time of X-chromosome inactivation, as previously stated. The assay of single hair follicles is, however, a very valuable tool for establishing the role of cell selection in the same or in a different tissue, like peripheral blood.

Variability of red cell phenotypes between and within individuals in an unbiased sample of 77 heterozygotes for G6PD deficiency in Sardinia

The distribution of G6PD red blood phenotypes in an unbiased sample of 77 Sardinian certain heterozygotes for the GdMediterranean mutant was found to be skewed in favor of the G6PD (+) cells. Four of these individuals exhibited the normal hemizygous phenotype in all of their cells, but two of them had a mosaic population of G6PD (+) and (-) red blood cells when reexamined after 1 year. These findings suggest that somatic selection may be the main factor determining the phenotype variability of individual somatic cells in highly differentiated tissues of heterozygotes at the G6PD locozygotes for the GdMediterranean mutant should not be used as a criterion for precise estimation of the embryonic or stem tissue cell pool at X inactivation.

[The clinical and radiological pictures of ulcerative colitis and Crohn's disease (author's transl)]

The differential diagnosis of ulcerative colitis and Crohn's disease is discussed in the light of the clinical and radiological pictures noted in 16 cases. A number of radiographs are presented.

Oxidation of selenocystamine by diamineoxidase

Selenocystamine is oxidatively deaminated by pig kidney diamineoxidase. The first product of the reaction is the corresponding cyclized aminoaldehyde, selenocystaldimine, which then undergoes further degradation. The oxidative deamination is thus the first step of a series of cyclic reactions which give rise to extensive cleavage of selenocystamine.

Oxidation of S-e-carboxymethyl-selenocysteine by L-aminoacid oxidase and by D-aspartate oxidase

Se-Carboxymethyl-DL-selnocysteine (CMSeC) has been prepared in a pure crystalline form from selenocysteine and monochloracetic acid. It has been shown that CMSeC is a substrate for the L-aminoacid oxidase form snake venom and for the D-aspartate oxidase from beef kidney. Oxygen consumption and ammonia production indicate that only the L or the D form of CMSeC ar acted upon respectively by one or the other of the above enzymes. No noticeable differences were shown in the oxidation rate of CMSeC and S-carboxymethylcysteine, an indication that the substitution of a selenium for a sulfur atom in the molecule does not greatly affect the substrate specificity of the two enzymes. Data have been obtained suggesting that the product of the oxidative deamination of CMSeC Is Se-carboxymethyl-selenopyruvic acid.

Synthesis of selenocystathionamine and preliminary data on its oxidation by diamineoxidase

Details are reported for the synthesis of selenocystathionamine, the 2-aminoethyl, 3-aminopropyl selenide, NH2CH2CH2-Se-CH2CH2CH2NH2. Paper and ion exchange chromatographic behaviour of the compound has been investigated. By automated ion exchange chromatography on a sulfonated resin selenocystathionamine may be easily differentiated from cystathionamine, cystamine and selenocystamine. It has been shown that selenocystathionamine is oxidatively deaminated by pig kidney diamineoxidase. Preliminary data indicate that the first product of the reaction is a cyclized aminoaldehyde which then undergoes further degradation.

Copper catalyzed alkaline autoxidation of selenocystamine

In alkaline medium and in the presence of cupric ions selenocystamine undergoes autoxidation and is entirely transformed into selenohypotaurine. Among the different metal ions tested, Fe, Co, Ni, Cu, Ag, Mg, Mn, only cupric ions are effective in catalyzing the reaction. The reaction shows an optimum around pH 13. In most respects the autoxidation of selenocystamine is similar to the alkaline autoxidation of cystamine. Some data on the paper and ion exchange chromatographic behaviour of selenohypotaurine and selenotaurine are reported, as also details for the synthesis of selenotaurine.

Synthesis and chromatographic properties of cysthationamine. A substrate for diamineoidase

Details are reported for the preparation of the 2-aminoethyl, 3-aminopropyl sulfide from 3-bromopropylamine and 2-mercaptoethylamine. For this compound, the shorter name cystathionamine is proposed. The corresponding sulfoxide and sulfone have been also prepared. Some analytical data and chromatographic properties are reported. Preliminary results show that cystathionamine is a good substrate for the pig kidney diamineoxidase.

Tissue-specific glucose 6-phosphate dehydrogenases in anopheline mosquitoes

Glucose 6-phosphate dehydrogenase (G6PD) electrophoretic variants have been detected in single adult homogenates by screening laboratory strains of Anopheles atroparvus, Anopheles labranchiae and Anopheles stephensi. Pair mating crosses of A. atroparvus individuals set up to study the inheritance mechanism of this apparent polymorphism failed to show Mendelian segregation. Furthermore, monomorphic and tissue-specific G6PD bands were obtained from single adult "midgut" and single adult "skin" homogenates and the apparent polymorphism disappeared. However, the electrophoretic heterogeneity reappeared when 10 µl of the gut homogenate were added to an equal volume of the skin homogenate and permitted to interact in vitro at room temperature (20-25°C) for 4-5 min. Bovine trypsin greatly modified the anodical mobility of the skin isoenzyme. Single whole homogenates, prepared in buffers containing soybean (trypsin inhibitor), partially retained the electrophoretic heterogeneity. On this experimental background it is possible to draw the following conclusions: (a) at least two monomorphic and tissue-specific (gut and skin) G6PD isoenzymes are present in the anopheline species studied by us; (b) a factor (or factors) possessing a trypsin-like action seems to be present in the whole body homogenate, this factor seems to be particularly active in interacting with the skin enzyme; and (c) the occurrence of a similar interaction could facilitate the formation of G6PD catalytically active molecular artifacts. These data and analogous results obtained by other authors permitted us to conclude that if genetic analysis has not been performed it is very hazardous to interpret zymograms simply by assuming that any electrophoretic heterogeneity necessarily represents a genetic polymorphism.