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    Björn Palmgren

    Since in mammals, the hair cells or the spiral ganglion neurons (SGNs) in the inner ear do not regenerate, damage to these cells is an irreversible process. Presently the only aid for patients with severe to profound hearing impairment... more
    Since in mammals, the hair cells or the spiral ganglion neurons (SGNs) in the inner ear do not regenerate, damage to these cells is an irreversible process. Presently the only aid for patients with severe to profound hearing impairment due to damaged hair cells is a cochlear implant (CI). A CI converts sound to electrical signals that stimulate the SGNs via an electrodes that is implanted into the cochlea. Hence, for a successful outcome the CI is dependant on the activation of the auditory nerve. There are several conditions, diseases or even traumatic events that primarily may impair the function of the SGNs in the auditory nerve. It is also known that in the absence of nerve stimuli due to hair cell damage, the SGNs will eventually degenerate. Lately there has been an increasing interest in regenerative medicine and bioengineering. This thesis presents results from in vivo experiments aiming to replace or repair the injured SGNs with the use of transplanted stem cells or neuronal...
    Genterapi vid genetiskt orsakad horselnedsattning[Gene therapy in hereditary hearing loss. Future therapeutic possibility--maybe combined with stem cells]
    Abstract Background and aims: Stage II cancer of the tongue is mostly managed surgically both locally and regionally. However, indications for postoperative radiotherapy and reconstructive options vary between centers. This paper aims to... more
    Abstract Background and aims: Stage II cancer of the tongue is mostly managed surgically both locally and regionally. However, indications for postoperative radiotherapy and reconstructive options vary between centers. This paper aims to describe differences in treatment in a geographically homogenous cohort. Methods: A retrospective comparison was made between two cohorts of clinical T2N0 tongue cancer from Finland and Sweden. The Finnish cohort included 75 patients and the Swedish 54. All patients had curative intent of treatment and no previous head and neck cancer. Data analyzed consisted of pathological stage, size and thickness of tumor, frequency of reconstruction, radiotherapy delivered, and survival. Results: The Finnish cohort included a higher proportion of patients managed with reconstructive surgery (67%) than the Swedish cohort (0%), p < .00001. More patients were treated with postoperative radiotherapy (84%) in the Swedish cohort than in the Finnish (54%), p < .0002. The Finnish cohort had a higher level of survival and included more frequent downstaging (cTNM to pTNM). Conclusions and significance: Our data indicate a major difference in the management of T2N0 oral tongue cancer. The optimal cut-off size and growth pattern of the tumor warranting reconstruction should be further evaluated in a prospective manner considering both survival and quality of life.
    The poor regeneration capability of the mammalian hearing organ has initiated different approaches to enhance its functionality after injury. To evaluate a potential neuronal repair paradigm in the inner ear and cochlear nerve we have... more
    The poor regeneration capability of the mammalian hearing organ has initiated different approaches to enhance its functionality after injury. To evaluate a potential neuronal repair paradigm in the inner ear and cochlear nerve we have previously used embryonic neuronal tissue and stem cells for implantation in vivo and in vitro. At present, we have used in vitro techniques to study the survival and differentiation of Sox1-green fluorescent protein (GFP) mouse embryonic stem (ES) cells as a monoculture or as a coculture with rat auditory brainstem slices. For the coculture, 300 microm-thick brainstem slices encompassing the cochlear nucleus and cochlear nerve were prepared from postnatal SD rats. The slices were propagated using the membrane interface method and the cochlear nuclei were prelabeled with DiI. After some days in culture a suspension of Sox1 cells was deposited next to the brainstem slice. Following deposition Sox1 cells migrated toward the brainstem and onto the cochlear nucleus. GFP was not detectable in undifferentiated ES cells but became evident during neural differentiation. Up to 2 weeks after transplantation the cocultures were fixed. The undifferentiated cells were evaluated with antibodies against progenitor cells whereas the differentiated cells were determined with neuronal and glial markers. The morphological and immunohistochemical data indicated that Sox1 cells in monoculture differentiated into a higher percentage of glial cells than neurons. However, when a coculture was used a significantly lower percentage of Sox1 cells differentiated into glial cells. The results demonstrate that a coculture of Sox1 cells and auditory brainstem present a useful model to study stem cell differentiation.