Manifestation of molar-incisor hypomineralisation in twins: clinical case reports

Molar-incisor hypomineralisation is a qualitative defect of dental tissue of systemic origin affecting one or more permanent first molars and sometimes the permanent incisors as well. There are still no conclusive data on the aetiology of this hypomineralisation, however, systemic factors such as respiratory diseases and prenatal and perinatal complications are regarded as possible causes. The objective is to present three clinical cases of twins, one Monozygotic and two Dizygotic Twins with molar-incisor hypomineralisation, showing evidence of its manifestation as well as clinical the characteristics and aetiological factors involved. The clinical findings involving twins suggest that ameloblasts are specifically affected in their developmental phase, which includes a number of factors. Although prenatal and perinatal complications are not decisive in the development of molar-incisor hypomineralization, it is suggested a possible genetic susceptibility to the disease. Prospective observational studies using a population sample containing data on the last three months of gestation to the eruption of permanent teeth are needed to confirm the causeeffect relationships.

Epigenetic and genetic approach to the transmissibility of dental characteristics in twins: report of two cases

Transmissibility of dental and jaw characteristics is strongly influenced by environmental factors during the years of extra uterine life when odontogenesis occurs. Through biochemical factors, such as enzymes, proteins, hormones and other mediators, genes are activated or silenced to suit the cell or organism to its environment. These changes are not transmitted to our descendants, because of that, these factors are called epigenetic. Among the most cited epigenetic factors are food, pollution, drugs and exercise. The objective of this study was to assess the transmissibility of dental characteristics in two pairs of twins. In one case, 13-year-old boys had the same basic dental and jaw characteristics with prolonged retention of the second upper deciduous molars and the presence of permanent successors. In the other case, 14-year-old boys had prolonged retention of lower deciduous second molars and absence of permanent successors, but only one of them had the germs of third lower molars. The phenotypic difference in the dentition of twins from clinical case 2 could be due to epigenetic factors, showing the absence of genetic determinism in the transmissibility of dental characteristics.

Identical sequence patterns in the ends of exons and introns of human protein-coding genes

Intron splicing is one of the most important steps involved in the maturation process of a pre-mRNA. Although the sequence profiles around the splice sites have been studied extensively, the levels of sequence identity between the exonic sequences preceding the donor sites and the intronic sequences preceding the acceptor sites has not been examined as thoroughly. In this study we investigated identity patterns between the last 15 nucleotides of the exonic sequence preceding the 5' splice site and the intronic sequence preceding the 3' splice site in a set of human protein-coding genes that do not exhibit intron retention. We found that almost 60% of consecutive exons and introns in human protein-coding genes share at least two identical nucleotides at their 3' ends and, on average, the sequence identity length is 2.47 nucleotides. Based on our findings we conclude that the 3' ends of exons and introns tend to have longer identical sequences within a gene than when being taken from different genes. Our results hold even if the pairs are non-consecutive in the transcription order. (C) 2012 Elsevier Ltd. All rights reserved.

Decoherence of quantum kinematical correlations: Elastic scattering of identical particles

We include the dynamics of the angular straggling process in the angular distributions of Mott scattering of heavy ions. We model the passage of an incoming nucleus through a target as a diffusion process. It is then possible to derive a simple and physically transparent expression for the angular dispersion due to the straggling. The angular dispersion should be folded with the theoretical Mott cross section to see its effect on the amplitude of the Mott oscillations. Our results agree very well with data of Pb-208 + Pb-208 scattering. We define the "classical" limit as the limit when the angular dispersion due to straggling becomes comparable with the Mott oscillation period and get the disappearance of quantum interference occurring at the limit 0.050 root xi Z(4)/E-3/2 >= 1, where xi stands for the target thickness, Z is the system's charge, and E is the center-of-mass energy. The experiments on lead are very close to this limit. We show that the kinematical correlations due to the identity of the particles is maintained, as it should be, and the action of the environment is to reduce the fringe visibility.

Bilateral mesiodens in monozygotic twins: 3D diagnostic and management

Mesiodens is the most frequent type of supernumerary tooth and may occur in several forms, causing different local disorders, such as impaction of the anterior permanent teeth. High-resolution three-dimensional (3D) images have improved the diagnosis and treatment plan of patients with impacted and supernumerary teeth. The purpose of this paper was to report a case of two mesiodens in monozygotic twin boys with appropriate 3D diagnostic and treatment plan

Should extragonadal germ cell tumors be included in studies of families with testicular germ cell tumors?

Abstract Background Family history is among the few established risk factors for testicular germ cell tumor (TGCT). Approximately 1.4% of newly diagnosed TGCT patients report a positive family history of TGCT. Sons and siblings of TGCT patients have four- to six fold and eight- to tenfold increase in TGCT risk, respectively. In twins of men with TGCT the relative risk of testicular cancer is 37.5 (12.3-115.6). Nevertheless, information about the occurrence of TGCT in relatives of patients with extragonadal germ cell tumor is limited. Case report A 24 year-old male patient was diagnosed with a mediastinum tumor and was submitted to image-guided biopsy, which revealed a seminoma. Two months later, his non-identical asymptomatic twin brother was submitted to an elective ultrasound of the testes, which showed a left testicular mass of 4.2 cm. This patient underwent orchiectomy revealing a seminoma of the left testis. There are no other cases of seminoma or other types of cancers reported in first-degree relatives in this family. Conclusions Although familial aggregations of TGCT have been well described, to the best of our knowledge, no data concerning the association of gonadal and extragonadal germ cell tumor in relatives has been previously reported. Further investigation on this association is warranted and may help in improving our knowledge of familial pattern inheritance.

ABO histo-blood group antigen expression on the graft endothelium long term after ABO-compatible, non-identical heart transplantation

We recently reported a complete change in the endothelial ABO histo-blood group phenotype of a cardiac allograft long term after B to O mismatched transplantation. In the context of the current controversy on graft recolonization with recipient endothelial cells and its importance in the development of immunological unresponsiveness, we monitored the expression of endothelial ABH histo-blood group antigens of 10 ABO-compatible, non-identical cardiac allografts over an observation period of at least 30 months. ABH antigens as well as markers for endothelial cells, erythrocytes and thrombocytes were investigated retrospectively by immunohistochemistry using monoclonal antibodies on sections of formalin-fixed, paraffin-embedded biopsies and were evaluated semi-quantitatively by microscopy. In contrast to our earlier finding of the change in the endothelial ABO histo-blood group phenotype long term after ABO- mismatched transplantation, we could not confirm this change in 10 compatible but non-identical cases.

The end1 gene of Schizosaccharomyces pombe coding for a DNase is identical with the pnu1 gene coding for an RNase

The DNA nuclease activity encoded by the end1 gene, and its inactivation by mutation, was described in connection with the characterization of DNA topoisomerases in the fission yeast Schizosaccharomyces pombe (Uemura and Yanagida, 1984). Subsequently, end1 mutant strains were used for the preparation of cell extracts for the study of enzymes and intermediates involved in DNA metabolism. The molecular identification of the end1 gene and its identity with the pnu1 gene is presented. The end1-458 mutation alters glycine to glutamate in the conserved motif TGPYLP. The pnu1 gene codes for an RNase that is induced by nitrogen starvation (Nakashima et al., 2002b). Thus, the End1/Pnu1 protein, like related mitochondrial proteins in other organisms, is an example of a sugar-non-specific nuclease. The analysis of strains carrying a pnu1 deletion revealed no defects in meiotic recombination and spore viability.