Molecular genetics of Usher syndrome -inherited deafness and blindness

Usher syndrome (USH) is an inherited blindness and deafness disorder with variable vestibular dysfunction. The syndrome is divided into three subtypes according to the progression and severity of clinical symptoms. The gene mutated in Usher syndrome type 3 (USH3), clarin 1 (CLRN1), was identified in Finland in 2001 and two mutations were identified in Finnish patients at that time. Prior to this thesis study, the two CLRN1 gene mutations were the only USH mutations identified in Finnish USH patients. To further clarify the Finnish USH mutation spectrum, all nine USH genes were studied. Seven mutations were identified: one was a previously known mutation in CLRN1, four were novel mutations in myosin VIIa (MYO7A) and two were a novel and a previously known mutation in usherin (USH2A). Another aim of this thesis research was to further study the structure and function of the CLRN1 gene, and to clarify the effects of mutations on protein function. The search for new splice variants resulted in the identification of eight novel splice variants in addition to the three splice variants that were already known prior to this study. Studies of the possible promoter regions for these splice variants showed the most active region included the 1000 bases upstream of the translation start site in the first exon of the main three exon splice variant. The 232 aa CLRN1 protein encoded by the main (three-exon) splice variant was transported to the plasma membrane when expressed in cultured cells. Western blot studies suggested that CLRN1 forms dimers and multimers. The CLRN1 mutant proteins studied were retained in the endoplasmic reticulum (ER) and some of the USH3 mutations caused CLRN1 to be unstable. During this study, two novel CLRN1 sequence alterations were identified and their pathogenicity was studied with cell culture protein expression. Previous studies with mice had shown that Clrn1 is expressed in mouse cochlear hair cells and spiral ganglion cells, but the expression profile in mouse retina remained unknown. The Clrn1 knockout mice display cochlear cell disruption/death, but do not have a retinal phenotype. The zebrafish, Danio rerio, clrn1 was found to be expressed in hair cells associated with hearing and balance. Clrn1 expression was also found in the inner nuclear layer (INL), photoreceptor layer and retinal pigment epithelium layer (RPE) of the zebrafish retina. When Clrn1 production was knocked down with injected morpholino oligonucleotides (MO) targeting Clrn1 translation or correct splicing, the zebrafish larvae showed symptoms similar to USH3 patients. These larvae had balance/hearing problems and reduced response to visual stimuli. The knowledge this thesis research has provided about the mutations in USH genes and the Finnish USH mutation spectrum are important in USH patient diagnostics. The extended information about the structure and function of CLRN1 is a step further in exploring USH3 pathogenesis caused by mutated CLRN1 as well as a step in finding a cure for the disease.

Viitotut elämät : Kuurojen nuorten aikuisten kokemuksia viittomakielisestä elämästä Suomessa

The goal of the study is to build an image of deafness and of the lives of the deaf from their own per-spectives. The lives of deaf sign language users are analysed through the concept of identity. The start-ing point for the study is the idea that identities are moulded and structured in action and interaction and are, therefore, continuous processes. The terminology and ideas used in the present study are mostly based on Erving Goffman s (1971, 1986) work in which he sees identity as a representation of self. Via our language and our actions we build and present an image of ourselves to others and to ourselves alike. The research aims at answering the following questions concerning the lives of deaf sign language users: how do deaf people build an image of themselves as deaf people, what kind of meanings does deafness acquire in their lives, and what opportunities do they have to be perceived by others as they feel they are, i.e. to present their true self . In order to answer these questions, the narratives provided by eighteen deaf young adults, aged 25 35, in narrative interviews carried out in sign language, have been analysed. The methodology used is that of a data-based, qualitative analysis and narrative analy-sis. The study follows the lines of prior qualitative research carried out in the field of sociology of health and in the study of everyday life. The subjects are divided into three groups according to the linguistic environment dominant in the family: 1) a deaf child in a deaf family, 2) a deaf child in a hearing family using sign language, and 3) a deaf child in a hearing family where sign language was not used. The childhood family has great significance in the way a child constructs his or her identity as a deaf person. The process of construct-ing an identity in the first group can be defined as being automatic or inherited, in the second group the process can be described as being a collective/joint identity-building process, whereas in the third group the process is ambivalent and delayed. The opportunities the deaf have in building their identi-ties as deaf people have been examined through the concept of a collective story reservoir. Research shows that the deaf have, at least partly, a different collective story reservoir that they can rely on from the one the hearing have. Interaction with other deaf people and access to the collective story reservoir is important, because it enables the deaf to form an idea of their own deafness and the life of a deaf person. Three different ways of understanding deafness can be conceptualized from the narratives of the inter-viewed deaf people. In the outdated counter-narrative and the reductive narrative of deafness as an abnormality, the subjects are not capable of seeing themselves as forming part of the narratives or identifying themselves with the ways the deaf are depicted. Yet, the characterizations prevalent in them are the ones that the deaf constantly come across in their day-to-day lives. The narrative through which the subjects depict themselves and their lives can be defined as a pluralistic narrative. The plu-ralistic narrative consists of three elements: the coexistence of the world of the deaf and that of the hearing, the orientation to sign language, and the replacement of local networks with global networks. Although modern Finnish society and its varied social services and subsidy systems enable the realiza-tion of the kind of life described in the pluralistic narrative, the issues of power and inequality still frequently emerge in the narratives in which the deaf young adults described themselves and their lives. Two kinds of power mechanisms can be perceived in the descriptions: belittling and excluding power. These considerably diminish the opportunities of sign language users to create the kind of life that would reflect their personalities while limiting the chances for presenting the self to others.

Improving outcome of childhood bacterial meningitis by simplified treatment : Experience from Angola

Background Acute bacterial meningitis (BM) continues to be an important cause of childhood mortality and morbidity, especially in developing countries. Prognostic scales and the identification of risk factors for adverse outcome both aid in assessing disease severity. New antimicrobial agents or adjunctive treatments - except for oral glycerol - have essentially failed to improve BM prognosis. A retrospective observational analysis found paracetamol beneficial in adult bacteraemic patients, and some experts recommend slow β-lactam infusion. We examined these treatments in a prospective, double-blind, placebo-controlled clinical trial. Patients and methods A retrospective analysis included 555 children treated for BM in 2004 in the infectious disease ward of the Paediatric Hospital of Luanda, Angola. Our prospective study randomised 723 children into four groups, to receive a combination of cefotaxime infusion or boluses every 6 hours for the first 24 hours and oral paracetamol or placebo for 48 hours. The primary endpoints were 1) death or severe neurological sequelae (SeNeSe), and 2) deafness. Results In the retrospective study, the mortality of children with blood transfusion was 23% (30 of 128) vs. without blood transfusion 39% (109 of 282; p=0.004). In the prospective study, 272 (38%) of the children died. Of those 451 surviving, 68 (15%) showed SeNeSe, and 12% (45 of 374) were deaf. Whereas no difference between treatment groups was observable in primary endpoints, the early mortality in the infusion-paracetamol group was lower, with the difference (Fisher s exact test) from the other groups at 24, 48, and 72 hours being significant (p=0.041, 0.0005, and 0.005, respectively). Prognostic factors for adverse outcomes were impaired consciousness, dyspnoea, seizures, delayed presentation, and absence of electricity at home (Simple Luanda Scale, SLS); the Bayesian Luanda Scale (BLS) also included abnormally low or high blood glucose. Conclusions New studies concerning the possible beneficial effect of blood transfusion, and concerning longer treatment with cefotaxime infusion and oral paracetamol, and a study to validate our simple prognostic scales are warranted.

"Oma entinen on palannut takaisin elämään" : Kuntoutuksen vaikuttavuus aikuisena kuuroutuneiden henkilöiden elämänhallintaan ja psykososiaaliseen hyvinvointiin

Objective The objective of this study was to learn about the psychosocial well-being and life management of Finnish adults with late deafness or hearing loss and to observe the effectiveness of the rehabilitation courses they participated in. Methods For my study I used indicators which were suitable for the evaluation of life management and psychosocial well-being of late-deafened adults. The first part of the study was conducted during 2009 as a questionnaire on three rehabilitation courses in Kopola, a course center of the Finnish Federation of Hard of Hearing. The follow-up study was done at the third period of the courses during 2009 2010. The questionnaire contained both open and structured questions. The questionnaire consisted of five areas concerning life management and psychosocial well-being: sense of coherence (life management), human relations and social support, mood, self-esteem and satisfaction with life. I also asked the participants to reflect on their experiences of group rehabilitation. Results and conclusions The participants consisted of seven women and three men. They were approximately 63 years old and were all retired. Loss of hearing was described to have affected their social life, free time, and in general made their lives more difficult. From the course the participants hoped to gain new skills such as signed speech and lip-reading, uplift their mood, accept their loss of hearing and experience peer support. After the courses they replied that they had more close relations with whom they also were a little more in contact with. More participants were satisfied with e.g. their ability to take care of themselves, their free time, financial situation, family life, mental resources and physical shape. Majority of the participants showed symptoms of depression when the courses started, but at the end of the courses these signs had moderated or disappeared for most of them. The participants felt that during the rehabilitation they had been heard, respected, accepted and been taken care of. The course provided the possibility for confiding, and the discussions gave the participants support and consolidation. In conclusion, the course affected positively on the acclimatization to the hearing loss and the empowerment of the participants. The results of this study can be utilized in disability services, the development of rehabilitation and in the social- and health services of senior citizens.

Functional regulation of the Neurofibromatosis 2 tumor suppressor merlin

Neurofibromatosis 2 (NF2) is an autosomal dominant disorder manifested by the formation of multiple benign tumors of the nervous system. Affected individuals typically develop bilateral vestibular schwannomas which lead to deafness and balance disorders. The syndrome is caused by inactivation of the NF2 tumor suppressor gene, and mutation or loss of the NF2 product, merlin, is sufficient for tumorigenesis in both hereditary and sporadic NF2-associated tumors. Merlin belongs to the band 4.1 superfamily of cytoskeletal proteins, which also contain the related ezrin, radixin, and moesin (ERM) proteins. The ERM members provide a link between the cell cytoskeleton and membrane by connecting membrane-associated proteins to actin filaments. By stabilizing complexes in the cell cortex, the ERMs modulate morphology, growth, and migration of cells. Despite their structural homology, overlapping subcellular distribution, direct molecular association, and partial overlap of molecular interactions, merlin and ezrin exert opposite effects on cell proliferation. Merlin suppresses cell proliferation, whereas ezrin expression is linked to oncogenic activity. We hypothesized that the regions which differ between the proteins might explain merlin s specificity as a tumor suppressor. We therefore analyzed the regions, which are most diverse between merlin and ezrin; the N-terminal tail and the C-terminus. To determine the properties of the C-terminal region, we studied the two most predominant merlin isoforms together with truncation variants similar to those found in patients. We also focused on the evolutionally conserved C-terminal residues, E545-E547, that harbor disease causing mutations in its corresponding DNA sequence. In addition to inhibiting cell proliferation, merlin regulates cytoskeletal organization. The morphogenic properties of merlin may play a role in tumor suppression, since patient-derived tumor cells demonstrate cytoskeletal abnormalities. We analyzed the mechanisms of merlin-induced extension formation and determined that the C-terminal region of amino acids 538-568 is particularly important for the morphogenic activity. We also characterized the role of C-terminal merlin residues in the regulation of proliferation, phosphorylation, and intramolecular associations. In contrast to previous reports, we demonstrated that both merlin isoforms are able to suppress cell proliferation, whereas C-terminally mutated merlin constructs showed reduced growth inhibition. Phosphorylation serves as a mechanism to regulate the tumor suppressive activity of merlin. The C-terminal serine 518 is phosphorylated in response to both p21-activated kinase (PAK) and protein kinase A (PKA), which inactivates the growth inhibitory function of merlin. However, at least three differentially phosphorylated forms of the protein exist. In this study we demonstrated that also the N-terminus of merlin is phosphorylated by AGC kinases, and that both PKA and Akt phosphorylate merlin at serine 10 (S10). We evaluated the impact of this N-terminal tail phosphorylation, and showed that the phosphorylation state of S10 is an important regulator of merlin s ability to modulate cytoskeletal organization but also regulates the stability of the protein. In summary, this study describes the functional effect of merlin specific regions. We demonstrate that both S10 in the N-terminal tail and residues E545-E547 in the C-terminus are essential for merlin activity and function.