Biomedical subjects
Publications and source records attributed to L Ulizzi.
The secular trend of stabilizing selection on birth weight has been studied during the last decades in 17 countries, representative of America, Asia and Europe. A relaxation of the intensity of selection is regularly observed, which can probably be attributed to a progressive reduction of the environmental component of birth weight variance.
Explore the source record for details and available documents.
Italy, like other industrialized countries, experienced during the last century a dramatic change in socio-economic conditions and in sanitation. In order to ascertain whether the improvement in living conditions has modified the relationships between the sex ratio at birth and selection by early mortality (stillbirth, mortality up to 1 month, mortality up to 1 year of life), the secular trends of the sex ratio in total births, in survivors up to 1 month and up to 1 year of age have been calculated for the Italian population over the last century. The results can be summarized as follows: (i) the sex ratio in total births progressively decreases; (ii) the sex ratio in survivors up to 1 year progressively increases. As a result of these two opposite trends, the difference between sex ratio at birth and after the incidence of early mortality is progressively getting smaller.
Differential mortality as a function of birth weight was studied up to the 4th week of life in all single births in Italy in 1974. It was found that: (i) Both selection intensity and selective mortality are much higher with increasing immaturity. (ii) For babies born at term or after 8 months of pregnancy selection intensity tends to relax as early as one week after birth, while for those born after 7 months selection is at work for a longer period. (iii) Selective mortality, on the other hand, keeps increasing after birth but its relevance is relatively decreasing since average mortality after birth continues to decrease.
The differences of birth-weight distributions before and after selection by the different components of perinatal mortality were studied for all single babies born in Italy in 1974. It was found that: (i) In mature babies the selection is mainly stabilizing while the directional type is almost negligible. (ii) In immature babies both stabilizing and directional selection are at work, greatly modifying the birth weight distributions.
Differential stillbirth rates as a function of birth-weight have been studied in all single births in Italy in the years, 1954, 1961, 1967 and 1974. In the course of the twenty year interval of observation the following changes were found: (i) a progressive equalization of mortality in birth-weight classes near the mean; (ii) a reduction of the directional component of selection which is parallel to the increase of mean birth-weight (in the case of 8 months of pregnancy); (iii) a reduction of the stabilizing component of selection which is parallel to the decrease of birth-weight variance (in the case of 9 months of pregnancy); (iv) a reduction of selection intensity, while selective mortality remains more or less unchanged. The modifications of natural selection associated with birth-weight as consequence of health care progress in this population are also discussed.
Phosphoglucomutase electrophoretic patterns have been studied in 60 tail homogenates of Triturus cristatus carnifex. Our results show that the same sample produces a different electrophoretic pattern with homogenate ageing; a new band of intermediate mobility appears, together with the one produced by the fresh preparation. The phenomenon can mimic a true genetic polymorphism when differently stored samples are analyzed.
The index of opportunity for selection proposed by Crow has been calculated for the Italian population during the last century. The evolution of its two components, the pre-reproductive mortality and the variance in fertility, has been also analysed and compared with similar data for the United States. The results clearly show the relevance of socio-economic changes to the evolution of selective patterns in our species; in particular the relative incidence of mortality and fertility to selection intensity: the total index has in fact been reduced by 75% during the last century, the relative amount due to fertility increasing from 57 to 89%. The probable different relevance of genetic factors in the two components has also been discussed.
The mortailty and fertility components of the index of opportunity for selection (the Crow index) have been studied in the various Italian regions during the last century. To estimate the relevance of environmental factors on both components, their trends and those of their interregional variances have been compared with illiteracy. The results show that the selection opportunities due to mortality have decreased in a smiliar way in all the regions with a trend parallel to that of the national percentage of illiteracy, suggesting that this component is directly affected by the general socio-cultural level. As to the component due to fertility differentials, the regions, though scattered in the time scale, show a characteristic cycle of rise and fall. Moreover, the interregional variances of this component and of illiteracy are quite parallel, thus supporting the hypothesis that the reproductive pattern is strongly influenced by the individual cultural level.
1218 individuals from Sardinia island (Italy) were tested for Gm and Km markers; 10 were not tested for Gm and only 401 were typed for Am markers. The peculiar genetic makeup of the Sardinian population is confirmed by their Gm allotypes. Their differences from those found in a control population of continental Italy (Ferrara), suggest ancient contacts with the Middle East and Africa. An indication for such contacts may also be found in the striking presence of the haplotype Gm f;n;bsc5, a haplotype not previously found in a human population. A significant difference of G2m(n) allotype was observed between highland and lowland regions. If confirmed, it may suggest an adaptive pressure related to the CH2 region of the gamma2 chain, possibly due to endemic malaria in the past.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
The secular trend of stature in Italy from 1874 to 1960 has been examined using military records concerning nearly complete samples of males born in Italy in given years. The national mean value increased by nine cm (about one cm/decade) and the averages of the different Italian regions tend progressively to aggregate towards higher values (the north) and lower ones (the south). The rate of increase of stature was more or less constant up to subjects born in 1945, but in the period 1945-55 a very steep increase was observed. In more recent times, a clear slowing down has taken place both at national and regional level. The following moments around the mean were investigated: (1) variance--the national value has remained more or less constant and regional values pass from very diverse figures to very similar ones; (2) skewness--the initially negative national value has become slightly positive; in the regions, from very diverse negative values a close aggregation around zero is recently attained; (3) kurtosis--initial national hyperkurtosis has reduced to values typical of the Normal distribution; the same is true for regional figures which, moreover, have become closely aggregated. The increasing fit of stature distribution to the Normal distribution agrees with the hypothesis of an increasing expression of the genetic endowment in consequence of a progressive improvement in living conditions.
In order to study the effect of mother's age on birthweight variance, data were collected from Official Vital Statistics of the USA, Japan and Italy. Birthweight means and variances were calculated for all single births and for live births only. The results demonstrated that birthweight variance regularly increases in babies born to mothers of increasingly older age (with the exception of the youngest mothers). Moreover, the higher the variance in all births, the more the variance diminishes after late fetal selection. Therefore, a feedback phenomenon takes place in the stabilizing component of selection, i.e. the difference between the variance of all births and that of live births. As a consequence, at least part of the higher number of fetal losses experienced by older mothers can be attributed to the increased birthweight variance of their children.
Explore the source record for details and available documents.
Blood group systems ABO, RH, MNS, KEL, FY, LU and P, red cell enzymes ACP1, PGM1, PGM2, ADA, DIA and PHI, serum markers GC, HP, IGHG1, IGHG3 and IGK were examined in about 900 individuals sampled in 11 Sardinian isolates. The genetic differentiation turned out to be relatively high and the relevance of selected and neutral genes has been evaluated.