Regeneration of the auditory nerve - a cell transplantation study

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 electrode 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 tissue. All transplanted cells were labeled with a green fluorescent protein facilitating identification in the host animal. Paper I presents a new animal model of selective auditory nerve injury with preserved hair cells. The lesion was induced in rats by the application of β-bungarotoxin to the round window niche. Immunohistochemical straining confirmed the loss of SGN while the hair cells were kept intact. The induced hearing impairment was verified by auditory brain stem response (ABR). Paper II presents a surgical approach for the injection of stem cells to the auditory nerve by the internal auditory meatus (IAM). It was shown that this approach does not significantly affect the hearing as verified by ABR. Further, neuronal tract tracing with the enzyme horseradish peroxidase illustrated that injection of selected substances may be distributed by intra-axonal transportation centrally to the brain stem as well as peripherally to the cochlea. Furthermore it was illustrated that statoacoustic ganglions transplanted by the IAM survived for up to five weeks, though in low numbers. No cells had migrated through the Schwann-glia transitional zone into the cochlea. Paper III presents an assessment of mouse tau-GFP embryonic stem cells transplantated to the auditory nerve trunk by the IAM or into the modiolus in previously deafened rats. It was shown that supplementary treatment of BDNF in a bioactive peptide amphiphile (PA) nanogel increased survival and neuronal differentiation of the transplanted cells. It was also demonstrated that supplement of the enzyme chondroitinase ABC in the PA gel facilitated migration of transplanted cells through the transitional zone. Paper IV presents the use of human neural progenitor cells for transplantation to the auditory nerve by the IAM. We further assessed supplement of BDNF in the PA gel. After three weeks, survival and differentiation of the transplanted cells were observed. After six weeks of survival the majority of the surviving cells had differentiated into neurons. The addition of BDNF in PA gel significantly increased both survival and differentiation. The transplanted cells migrated to the brainstem and formed neuronal profiles including extensive arborisation of nerve fibers in the vicinity of the cochlear nucleus. In conclusion, this thesis presents a new animal model for a selective lesion of the auditory nerve. Further, promising results were demonstrated regarding the possibility of replacing auditory SGNs including increased rates of survival and neuronal differentiation of the transplanted cells in the presences of BDNF. These results suggest for further studies on auditory nerve replacement but also for functional assessment of the transplanted cells

Evolution of P2A and P5A ATPases:ancient gene duplications and the red algal connection to green plants revisited

In a search for slowly evolving nuclear genes that may cast light on the deep evolution of plants, we carried out phylogenetic analyses of two well-characterized subfamilies of P-type pumps (P2A and P5A ATPases) from representative branches of the eukaryotic tree of life. Both P-type ATPase genes were duplicated very early in eukaryotic evolution and before the divergence of the present eukaryotic supergroups. Synapomorphies identified in the sequences provide evidence that green plants and red algae are more distantly related than are green plants and eukaryotic supergroups in which secondary or tertiary plastids are common, such as several groups belonging to the clade that includes Stramenopiles, Alveolata, Rhizaria, Cryptophyta and Haptophyta (SAR). We propose that red algae branched off soon after the first photosynthesizing eukaryote had acquired a primary plastid, while in another lineage that led to SAR, the primary plastid was lost but, in some cases, regained as a secondary or tertiary plastid

Migratory Passerine Birds as Reservoirs of Lyme Borreliosis in Europe

Birds host vector ticks and Borrelia species and vary in effectiveness as reservoirs

Dissemination of Spotted Fever Rickettsia Agents in Europe by Migrating Birds

Migratory birds are known to play a role as long-distance vectors for many microorganisms. To investigate whether this is true of rickettsial agents as well, we characterized tick infestation and gathered ticks from 13,260 migratory passerine birds in Sweden. A total of 1127 Ixodes spp. ticks were removed from these birds and the extracted DNA from 957 of them was available for analyses. The DNA was assayed for detection of Rickettsia spp. using real-time PCR, followed by DNA sequencing for species identification. Rickettsia spp. organisms were detected in 108 (11.3%) of the ticks. Rickettsia helvetica, a spotted fever rickettsia associated with human infections, was predominant among the PCR-positive samples. In 9 (0.8%) of the ticks, the partial sequences of 17kDa and ompB genes showed the greatest similarity to Rickettsia monacensis, an etiologic agent of Mediterranean spotted fever-like illness, previously described in southern Europe as well as to the Rickettsia sp.IrITA3 strain. For 15 (1.4%) of the ticks, the 17kDa, ompB, gltA and ompA genes showed the greatest similarity to Rickettsia sp. strain Davousti, Rickettsia japonica and Rickettsia heilongjiangensis, all closely phylogenetically related, the former previously found in Amblyomma tholloni ticks in Africa and previously not detected in Ixodes spp. ticks. The infestation prevalence of ticks infected with rickettsial organisms was four times higher among ground foraging birds than among other bird species, but the two groups were equally competent in transmitting Rickettsia species. The birds did not seem to serve as reservoir hosts for Rickettsia spp., but in one case it seems likely that the bird was rickettsiemic and that the ticks had acquired the bacteria from the blood of the bird. In conclusion, migratory passerine birds host epidemiologically important vector ticks and Rickettsia species and contribute to the geographic distribution of spotted fever rickettsial agents and their diseases

Evolution of P2A and P5A ATPases: ancient gene duplications and the red algal connection to green plants revisited

In a search for slowly evolving nuclear genes that may cast light on the deep evolution of plants, we carried out phylogenetic analyses of two well-characterized subfamilies of P-type pumps (P2A and P5A ATPases) from representative branches of the eukaryotic tree of life. Both P-type ATPase genes were duplicated very early in eukaryotic evolution and before the divergence of the present eukaryotic supergroups. Synapomorphies identified in the sequences provide evidence that green plants and red algae are more distantly related than are green plants and eukaryotic supergroups in which secondary or tertiary plastids are common, such as several groups belonging to the clade that includes Stramenopiles, Alveolata, Rhizaria, Cryptophyta and Haptophyta (SAR). We propose that red algae branched off soon after the first photosynthesizing eukaryote had acquired a primary plastid, while in another lineage that led to SAR, the primary plastid was lost but, in some cases, regained as a secondary or tertiary plastid

Treatment and outcome among patients with laryngeal squamous cell carcinoma in Stockholm-A population-based study

Objective Survival of patients with advanced laryngeal squamous cell carcinoma (LSCC) remains poor and management protocols warrant further development. We thus investigated treatment and outcome-related factors for LSCC in Stockholm, Sweden.Methods In a retrospective setting, 520 patients with LSCC diagnosed during 2000-2014, were included. Data on stage, treatment, and outcome were correlated with recurrence-free and overall survival (RFS and OS, respectively).Results Five-year OS for all patients was 65%. Five-year RFS for T1a, T1b, T2, T3, and T4 glottic LSCC was 90%, 91%, 77%, 47%, and 80%, respectively. The corresponding figures for T1, T2, T3, and T4 supraglottic LSCC were 64%, 66%, 64%, and 86%.Conclusion Patients with a T3 glottic LSCC had unexpectedly poor survival, especially when compared with patients with a T4 tumor. Patients with T4 disease were primarily treated with laryngectomy and postoperative radiotherapy (RT)/chemoradiotherapy (CRT), while most patients with T3 LSCC were treated with RT/CRT.Peer reviewe

Exogenous BDNF and Chondroitinase ABC Consisted Biomimetic Microenvironment Regulates Survival, Migration and Differentiation of Human Neural Progenitor Cells Transplanted into a Rat Auditory Nerve

Current putative regeneration oriented studies express possible role of stem cell based implantation strategy in the restoration of fundamental perception of hearing. The present work utilizes a rat auditory nerve (AN) directed transplantation of human neural progenitor cells (HNPCs) as a cell replacement therapy for impaired auditory function. Groups of b-bungarotoxin induced auditory function compromised female rats were used to transplant HNPCs in the nerve trunk. In the treatment groups, brain derived neurotrophic factor (BDNF), peptide amphiphile nanofiber bioactive gel (Bgel) and Chondroitinase ABC (ChABC), a digestive enzyme that cleaves the core of chondroitin sulphate proteoglycans, were added along with HNPCs while the control groups were with PA inert gel (Igel) and devoid of ChABC. Six weeks post transplantation survival, migration, and differentiation of HNPCs were studied and compared. The groups treated with BDNF and Bgel showed improved survival and differentiation of transplanted HNPCs while the ChABC treated group showed significant migration of HNPCs along the AN and elongation of neuronal fibers along the nerve towards the cochlear nucleus (CN) which was characterized by immunocytochemical markers for human Nuclei (HuN), human mitochondria (HuM) and neuronal β-tubulin (Tuj1). These findings show that addition of BDNF and ChABC consisted Bgel environment facilitated HNPC survival, migration and differentiation along the transplanted rat AN towards the CN. This transplantation strategy provides unique experimental validation for futuristic role of cell based biomaterial consisted neurotrophic factor application in clinically transferable treatment of sensorineural hearing loss (SNHL) along with cochlear implants (CI)

Characterization of a Pore-Forming Cytotoxin Expressed by Salmonella enterica Serovars Typhi and Paratyphi A

Cytolysin A (ClyA) is a pore-forming cytotoxic protein encoded by the clyA gene that has been characterized so far only in Escherichia coli. Using DNA sequence analysis and PCR, we established that clyA is conserved in the human-specific typhoid Salmonella enterica serovars Typhi and Paratyphi A and that the entire clyA gene locus is absent in many other S. enterica serovars, including Typhimurium. The gene products, designated ClyA(STy) and ClyA(SPa), show ≥90% amino acid identity to E. coli cytolysin A, ClyA(EC), and they are immunogenically related. The Salmonella proteins showed a pore-forming activity and are hence functional homologues to ClyA(EC). The chromosomal clyA(STy) gene locus was expressed at detectable levels in the serovar Typhi strains S2369/96 and S1112/97. Furthermore, in the serovar Typhi vaccine strain Ty21a, expression of clyA(STy) reached phenotypic levels, as detected on blood agar plates. The hemolytic phenotype was abolished by the introduction of an in-frame deletion in the clyA(STy) chromosomal locus of Ty21a. Transcomplementation of the mutant with a cloned clyA(STy) gene restored the hemolytic phenotype. To our knowledge, Ty21a is the first reported phenotypically hemolytic Salmonella strain in which the genetic determinant has been identified