Biomedical subjects
G Brenci
Publications and source records attributed to G Brenci.
Presence of an endothelioid tubelike structure at the interface of the amniotic membranes in twins with single and double placenta. Growth factors involvement.
A histomorphological study of the amniotic membranes in full-term twins with double and single placenta was carried out by means of the silver impregnation staining technique suitably modified. Specimens of interface of amniotic membranes were prepared by means of sections. The constant presence of a tubelike structure was observed. Proceeding from the amniotic cavity, the following histological layers were noted. 1) single layer of amniotic cells; 2) amorphic substance with fibrocytes; 3) single layer of endothelial cells. The same order of single layer is present in the amniotic membrane of the second fetus. This tubelike structure is present only in cases of twins with double placenta. If the placenta is single with two umbilical cords, the tubelike structure is not present and only a central amorphic substance surrounded by two single layers of amniotic cells is observed, to confirm the single embryogenetic derivation (monovular). Therefore, through this histological method, we can recognize the true single placenta of twin pregnancy from the pseudosingle placenta so said for the presence of adherences of adjoining surfaces that make it appear single. On the contrary, by manual dissection it is possible to identify a twin pregnancy with two placentae. From the physiological point of view, the walls of the tubelike structure have probably the function to realize exchanges of amniotic liquids between the two fetuses, so as to obtain a balance of electrolytic ions and of intercavity pressure. Growth factors (vascular endothelial factor) are probably involved in the genesis of the endothelial tubelike structure.
A stochastic model of the genetic predisposition to ageing: an application to twin data.
In previous papers a stochastic model of the ageing process has been proposed. Some genetic parameters (redundance, repair) have been used to explain the observed differential predisposition to the process and family heredity. Because the process is basically due to effective random mutations, any individual of the population would be predisposed differently to ageing according to the structure of his/her genome. In the present paper, the previous model is generalized to take into account an additional genetic parameter, namely, the stability against random mutations, defined as the probability that a random mutation in a codon would produce no mutation in the corresponding protein. Estimation problems connected with the model are approached on the basis of twin data in maximum likelihood estimation as well as in bayesian framework. Some comparisons between the two methods are reported.
[Socioeconomic status and chronic diseases of the aged. A multicenter study].
The above study was carried out in a population sample of 1250 elderly subjects living at home, from five Italian regions (Budrio in Emilia-Romagna, Ponte S. Nicolò in Veneto, Bernareggio in Lombardy, Sezze in Latiumm, Melito in Campania). The results obtained lead to the following conclusions: 1. The condition of loneliness appears to have a detrimental influence on health in both sexes. Among other consequences, loneliness leads to progressive spontaneous reduction of daily milieu and social requirements, as well as to an impression of dependence that cannot be easily overcome. 2. The study of the relationship between the presence or absence of chronic pathologies and legal title of domicile has shown that if the home is their own by legal property or usufruct this has a favorable influence, especially in males. Property also satisfies emotional needs, through the profound ties between personal history and certain places. 3. Positive changes in life style may have beneficial effects on the interaction between socio-economic variables and the onset of chronic pathologies, especially in old age.
Atrial activity and cardiovascular response to stress in triplets: short case report.
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High-resolution electrocardiography in twins affected by situs viscerum specularis: short case report.
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Teratomorphism in the urinary tract of MZ twins: short case report.
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Possible mechanism of the heredity of twinning.
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Plasma cholesterol response to a change in dietary fat intake: a collaborative twin study.
The rise of plasma cholesterol in response to an increase from 8 to 22.3% in saturated fatty acid of total intake was studied by comparing the concordance of change in pairs of young English and Italian monozygotic (33 pairs) and dizygotic (22 pairs) twins. LDL and total cholesterol rose about 0.6 mmol/l. All methods of analyses showed a marked genetic component influencing total and LDL cholesterol level. However, the genetic component of the increase in LDL and total cholesterol levels was small in Italy and absent in England. These results suggest that the response of plasma cholesterol to this dietary change is largely determined by environmental factors rather than inheritance.
High resolution atrial depolarization of MZ twins detected by surface signal averaging technique.
High resolution tracings of atrial depolarization can be obtained by surface signal averaging technique. A study was conducted on 4 male and 4 female healthy MZ twin pairs aged 10.4 +/- 1.3 yrs. Each subject underwent 3 or more recordings, at 10-days intervals. The essential reproducibility could be confirmed, with personal characteristics, as well as the reliability of the technique and the electrophysiological value of the spikes complex. In 3/8 pairs the cotwins showed a significant likeness of the atriogram, while in 5/8 pairs the tracings were not quite resembling between the twins and that is attributed to variations in the chronogenetic characteristics of MZ twins.
Heredity and infectious diseases: a twin study.
A concordance study of 6 infectious diseases of childhood has been carried out in a sample of 656 twin pairs classified by sex and zygosity. A new approach is proposed to estimate the respective influence of heredity and of common environment. The estimates thus obtained range from 86% hereditary component in the case of measles to 100% environmental component in the case of scarlet fever.
Miscellaneous clinical case reports in twins.
Three case reports are presented concerning 1) Albino MZ female twins, 2) Raynaud's syndrome in MZ female twins, and 3) Pseudohermaphroditism in MZ male twins.
Situs viscerum specularis in monozygotic twins.
A case is reported of a 14-year old male MZ twin pair, with only one partner affected by situs viscerum inversus, whereby the condition is termed situs viscerum specularis. The high degree of mirror imaging is seen as an abnormal variation of the biological time of the cleavage giving rise to MZ twinning. Electrocardiographic findings are presented and the biological implications of the condition are discussed.
Twins living apart test: progress report.
A new approach is proposed in twin research based on the study of twins who, though reared together, have subsequently lived apart for a period of at least five years. With respect to the more powerful study of twins reared apart, the twins living apart test has the advantages of being more realistic and affording easier access to sufficiently large samples. In this pilot study, the test has been applied to a sample of 92 monozygotic pairs now aged 35-45; 15 pairs were still living together and 77 had lived apart for over five years. As a first approach, comparisons have been made, in the cotwins of the two subsamples, with respect to the following traits: height, weight, presbyopia, presbyacusia, alcohol consumption, tobacco consumption, blood pressure (systolic and diastolic), dental caries, and hours of sleep.
[Chromatid exchanges as parameters of the chronon].
In chronogenetic theory different genes have a different stability ("ergon") which determines the duration ("chronon") of their action. The ergon/chronon of each gene is considered to be inherited. In order to verify whether genomic stability is a heritable trait, the frequency of sister chromatid exchanges (SCE) was observed in a sample of 12 MZ twin pairs distributed as follows: (formula; see text) The minimum intrapair variability as against the high interpair variability as to mean S.C.E. counts supports the hypothesis of genetic control on S.C.E. frequency. The increase in S.C.E. frequency in older pairs indicates the age-dependence of the phenomenon. The study will be extended to both DZ pairs and older twin pairs.
Twin research: past and present.
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Low birth weight in twins versus singletons: separate entities and different implications for child growth and survival.
The condition of low birth weight is compared in twins and in singletons in terms of birth weight distributions and with respect to factors such as the incidence of stillbirths, length of gestation, maternal age, parity, and legitimacy. In the light of demographic, biological, and developmental considerations, it is concluded that low birth weight in twins is a different condition from low birth weight in singletons and should be dealt with independently, especially in view of the different implications for child growth and survival.
Zygosity test based on growth measures: a Bayesian approach.
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