Molecular genetics of tooth agenesis

Congenital missing of teeth, tooth agenesis or hypodontia, is one of the most common developmental anomalies in man. The common forms in which one or a few teeth are absent, may cause occlusal or cosmetic harm, while severe forms which are relatively rare always require clinical attention to support and maintain the dental function. Observation of tooth agenesis is also important for diagnosis of malformation syndromes. Some external factors may cause developmental defects and agenesis in dentition. However, the role of inheritance in the etiology of tooth agenesis is well established by twin and family studies. Studies on familial tooth agenesis as well as mouse null mutants have also identified several genetic factors. However, these explain syndromic or rare dominant forms of tooth agenesis, whereas the genes and defects responsible for the majority of cases of tooth agenesis, especially the common and less severe forms, are largely unknown. In this study it was shown, that a dominant nonsense mutation in PAX9 was responsible for severe tooth agenesis (oligodontia) in a Finnish family. In a study of tooth agenesis associated with Wolf-Hirschhorn syndrome, it was shown that severe tooth agenesis was present if the causative deletion in 4p spanned the MSX1 locus. It was concluded that severe tooth agenesis was caused by haploinsufficiency of these transcription factors. A summary of the phenotypes associated with known defects in MSX1 and PAX9 showed that, despite similarities, they were significantly different, suggesting that the genes, in addition to known interactions, also have independent roles during the development of human dentition. The original aim of this work was to identify gene defects that underlie the common incisor and premolar hypodontia. After excluding several candidate genes, a genome-wide search was conducted in seven Finnish families in which this phenotype was inherited in an autosomal dominant manner. A promising locus for second premolar agenesis was identified in chromosome 18 in one family and this finding was supported by results from other families. The results also implied the existence of other loci both for second premolar agenesis and for incisor agenesis. On the other hand the results did not lend support for comprehensive involvement of the most obvious candidate genes in the etiology of incisor and premolar hypodontia. Rather, they suggest remarkable genetic heterogeneity of tooth agenesis. The available evidence suggests that quantitative defects during tooth development predispose to a failure to overcome a developmental threshold and to agenesis. The results of the study increase the understanding of the etiology and heredity of tooth agenesis. Further studies may lead to identification of novel genes that affect the development of teeth.

Synthesis of neoglycoconjugates and oligosaccharides with potential anti-Helicobacter pylori activity

The significance of carbohydrate-protein interactions in many biological phenomena is now widely acknowledged and carbohydrate based pharmaceuticals are under intensive development. The interactions between monomeric carbohydrate ligands and their receptors are usually of low affinity. To overcome this limitation natural carbohydrate ligands are often organized as multivalent structures. Therefore, artificial carbohydrate pharmaceuticals should be constructed on the same concept, as multivalent carbohydrates or glycoclusters. Infections of specific host tissues by bacteria, viruses, and fungi are among the unfavorable disease processes for which suitably designed carbohydrate inhibitors represent worthy targets. The bacterium Helicobacter pylori colonizes more than half of all people worldwide, causing gastritis, gastric ulcer, and conferring a greater risk of stomach cancer. The present medication therapy for H. pylori includes the use of antibiotics, which is associated with increasing incidence of bacterial resistance to traditional antibiotics. Therefore, the need for an alternative treatment method is urgent. In this study, four novel synthesis procedures of multivalent glycoconjugates were created. Three different scaffolds representing linear (chondroitin oligomer), cyclic (γ-cyclodextrin), and globular (dendrimer) molecules were used. Multivalent conjugates were produced using the human milk type oligosaccharides LNDFH I (Lewis-b hexasaccharide), LNnT (Galβ1-4GlcNAcβ1-3Galβ1-4Glc), and GlcNAcβ1-3Galβ1-4GlcNAcβ1-3Galβ1-4Glc all representing analogues of the tissue binding epitopes for H. pylori. The first synthetic method included the reductive amination of scaffold molecules modified to express primary amine groups, and in the case of dendrimer direct amination to scaffold molecule presenting 64 primary amine groups. The second method described a direct procedure for amidation of glycosylamine modified oligosaccharides to scaffold molecules presenting carboxyl groups. The final two methods that were created both included an oxime-linkage on linkers of different length. All the new synthetic procedures synthesized had the advantage of using unmodified reducing sugars as starting material making it easy to synthesize glycoconjugates of different specificity. In addition, the binding activity of an array of neoglycolipids to H. pylori was studied. Consequently, two new neolacto-based structures, Glcβ1-3Galβ1-4GlcNAcβ1-3Galβ1-4Glcβ1-Cer and GlcAβ1-3Galβ1-4GlcNAcβ1-3Galβ1-4Glcβ1-Cer, with binding activity toward H. pylori were discovered. Interestingly, N-methyl and N-ethyl amide modification of the GlcAβ1-3Galβ1-4GlcNAcβ1-3Galβ1-4Glcβ1-Cer glucuronic acid residue resulted in more effective H. pylori binding epitopes than the parent molecule.

Identification of loci for migraine with aura

Common migraine, i.e. migraine with (MA) or without aura (MO), is a chronic neurological disorder affecting about 10% of the Caucasian population. In MA, migraine headache is preceded by visual, sensoric and/or dysphasic reversible aura symptoms. Twin and family studies have suggested a multifactorial mode of inheritance for common migraine, and a stronger genetic component for MA than for MO. Since there is no biological or genetic marker to identify common migraine, aura symptoms provide a distinctive character to identify those suspected of suffering from migraine. The aim of this study was to identify MA susceptibility loci in well-phenotyped migraine samples with familial predisposition using different gene mapping methods. Genes coding for endothelin1 and its receptors EDNRA and ENDRB are potential candidate genes for cortical spreading depression (CSD), which is considered to be the underlying mechanism of migraine aura. The role of these genes in MA was studied in 850 Finnish migraine cases and 890 control individuals. Rare homozygous EDNRA SNPs showed nominal association with MA and with the age of onset trait (20 years). This result was also detected in the pooled analysis on 648 German MA cases and 651 control individuals when the test was adjusted for gender and sample origin. Evaluation of SNP genotyping reactions with two different DNA polymerase enzymes ensured that the genotype quality was high, and thus the discovered associations are considered reliable. The role of the 19p13 region was studied in a linkage analysis of 72 Finnish MA families. This region contains two migraine-associated genes: CACNA1A, which is associated with a predisposition to a rare Mendelian form of MA, familial hemiplegic migraine (FHM), and the insulin receptor gene (INSR) that is associated with common migraine. No evidence of linkage between the 19p13 and MA was detected. A novel visual aura locus was mapped to chromosome 9q21-q22 with significant evidence of linkage using a genome-wide linkage approach in 36 Finnish MA families. Five additional, potential loci were also detected. The 9q21-q22 region has previously been linked to occipitotemporal lobe epilepsy and MA, both of which involve prominent visual symptoms. Our result further supports a shared background for these episodic disorders.

Causes of death in patients with rheumatoid arthritis over a 40-year period : with special emphasis on autopsy

Rheumatoid arthritis (RA) patients have premature mortality. Contrary to the general population, mortality in RA has not declined over time. This study aimed to evaluate determinants of mortality in RA by examining causes of death (CoDs) over time, accuracy of CoD diagnoses, and contribution of RA medication to CoDs. This study further evaluated detection rate of reactive systemic amyloid A amyloidosis, which is an important contributor to RA mortality. CoDs were examined in 960 RA patients between 1971 and 1991 (Study population A) and in 369 RA patients autopsied from 1952 to 1991, with non-RA patients serving as the reference cases (Study population B). In Study population B, CoDs by the clinician before autopsy were compared to those by the pathologist at autopsy to study accuracy of CoD diagnoses. In Study population B, autopsy tissue samples were re-examined systematically for amyloidosis (90% of patients) and clinical data for RA patients was studied from 1973. RA patients died most frequently of cardiovascular diseases (CVDs), infections, and RA. RA deaths declined over time. Coronary deaths showed no major change in Study population A, but, in Study population B, coronary deaths in RA patients increased from 1952 to 1991, while non-RA cases had a decrease in coronary deaths starting in the 1970s. Between CoD diagnoses by the clinician and those by the pathologist, RA patients had lower agreement than non-RA cases regarding cardiovascular (Kappa reliability measure: 0.31 vs. 0.51) and coronary deaths (0.33 vs. 0.46). Use of disease modifying anti-rheumatic drugs was not associated with any CoD. In RA patients, re-examination of autopsy tissue samples doubled the prevalence of amyloid compared with the original autopsy: from 18% to 30%. In the amyloid-positive RA patients, amyloidosis was diagnosed before autopsy in only 37%; and they had higher inflammatory levels and longer duration of RA than amyloid-negative RA patients. Of the RA patients with amyloid, only half had renal failure or proteinuria during lifetime. In RA, most important determinants of mortality were CVDs, RA, and infections. In RA patients, RA deaths decreased over time, but this was not true for coronary deaths. Coronary death being less accurately diagnosed in RA may indicate that coronary heart disease (CHD) often goes unrecognized during lifetime. Thus, active search for CHD and its effective treatment is important to reduce cardiovascular mortality. Reactive amyloidosis may often go undetected. In RA patients with proteinuria or renal failure, as well as with active and long-lasting RA, a systematic search for amyloid is important to enable early diagnosis and early enhancement of therapy. This is essential to prevent clinical manifestations of amyloidosis such as renal failure, which has a poor prognosis.

Hybrid Modelling of Titan's Interaction with the Magnetosphere of Saturn

In this dissertation we study the interaction between Saturn's moon Titan and the magnetospheric plasma and magnetic field. The method of research is a three-dimensional computer simulation model, that is used to simulate this interaction. The simulation model used is a hybrid model. Hybrid models enable individual tracking or tracing of ions and also take into account the particle motion in the propagation of the electromagnetic fields. The hybrid model has been developed at the Finnish Meteorological Institute. This thesis gives a general description of the effects that the solar wind has on Earth and other planets of our solar system. Planetary satellites can also have similar interactions with the solar wind but also with the plasma flows of planetary magnetospheres. Titan is clearly the largest among the satellites of Saturn and also the only known satellite with a dense atmosphere. It is the atmosphere that makes Titan's plasma interaction with the magnetosphere of Saturn so unique. Nevertheless, comparisons with the plasma interactions of other solar system bodies are valuable. Detecting charged plasma particles requires in situ measurements obtainable through scientific spacecraft. The Cassini mission has been one of the most remarkable international efforts in space science. Since 2004 the measurements and images obtained from instruments onboard the Cassini spacecraft have increased the scientific knowledge of Saturn as well as its satellites and magnetosphere in a way no one was probably able to predict. The current level of science on Titan is practically unthinkable without the Cassini mission. Many of the observations by Cassini instrument teams have influenced this research both the direct measurements of Titan as well as observations of its plasma environment. The theoretical principles of the hybrid modelling approach are presented in connection to the broader context of plasma simulations. The developed hybrid model is described in detail: e.g. the way the equations of the hybrid model are solved is shown explicitly. Several simulation techniques, such as the grid structure and various boundary conditions, are discussed in detail as well. The testing and monitoring of simulation runs is presented as an essential routine when running sophisticated and complex models. Several significant improvements of the model, that are in preparation, are also discussed. A main part of this dissertation are four scientific articles based on the results of the Titan model. The Titan model developed during the course of the Ph.D. research has been shown to be an important tool to understand Titan's plasma interaction. One reason for this is that the structures of the magnetic field around Titan are very much three-dimensional. The simulation results give a general picture of the magnetic fields in the vicinity of Titan. The magnetic fine structure of Titan's wake as seen in the simulations seems connected to Alfvén waves an important wave mode in space plasmas. The particle escape from Titan is also a major part of these studies. Our simulations show a bending or turning of Titan's ionotail that we have shown to be a direct result of the basic principles in plasma physics. Furthermore, the ion flux from the magnetosphere of Saturn into Titan's upper atmosphere has been studied. The modelled ion flux has asymmetries that would likely have a large impact in the heating in different parts of Titan's upper atmosphere.

The Protection of Traditional Knowledge Associated with Genetic Resources: The Role of Databases and Registers

"The Protection of Traditional Knowledge Associated with Genetic Resources: The Role of Databases and Registers" ABSTRACT Yovana Reyes Tagle The misappropriation of TK has sparked a search for national and international laws to govern the use of indigenous peoples knowledge and protection against its commercial exploitation. There is a widespread perception that biopiracy or illegal access to genetic resources and associated traditional knowledge (TK) continues despite national and regional efforts to address this concern. The purpose of this research is to address the question of how documentation of TK through databases and registers could protect TK, in light of indigenous peoples increasing demands to control their knowledge and benefit from its use. Throughout the international debate over the protection of TK, various options have been brought up and discussed. At its core, the discussion over the legal protection of TK comes down to these issues: 1) The doctrinal question: What is protection of TK? 2) The methodological question: How can protection of TK be achieved? 3) The legal question: What should be protected? And 4) The policy questions: Who has rights and how should they be implemented? What kind of rights should indigenous peoples have over their TK? What are the central concerns the TK databases want to solve? The acceptance of TK databases and registers may bring with it both opportunities and dangers. How can the rights of indigenous peoples over their documented knowledge be assured? Documentation of TK was envisaged as a means to protect TK, but there are concerns about how documented TK can be protected from misappropriation. The methodology used in this research seeks to contribute to the understanding of the protection of TK. The steps taken in this research attempt to describe and to explain a) what has been done to protect TK through databases and registers, b) how this protection is taking place, and c) why the establishment of TK databases can or cannot be useful for the protection of TK. The selected case studies (Peru and Venezuela) seek to illustrate the complexity and multidisciplinary nature of the establishment of TK databases, which entail not only legal but also political, socio-economic and cultural issues. The study offers some conclusions and recommendations that have emerged after reviewing the national experiences, international instruments, work of international organizations, and indigenous peoples perspectives. This thesis concludes that if TK is to be protected from disclosure and unauthorized use, confidential databases are required. Finally, the TK database strategy needs to be strengthened by the legal protection of the TK itself.